diff --git a/CHANGES.rst b/CHANGES.rst
index 26214a18220..7f488907189 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,12 +4,17 @@ Release 7.4.0 (in development)
 Dependencies
 ------------
 
+* LaTeX: the ``xcolor`` package is now required.
+
 Incompatible changes
 --------------------
 
 Deprecated
 ----------
 
+* LaTeX: the ``sphinxlightbox`` environment is not used anymore, all types
+  of admonitions use ``sphinxheavybox``.
+
 Features added
 --------------
 
diff --git a/sphinx/texinputs/sphinx.sty b/sphinx/texinputs/sphinx.sty
index 6c31f329c65..e426597f10a 100644
--- a/sphinx/texinputs/sphinx.sty
+++ b/sphinx/texinputs/sphinx.sty
@@ -3,10 +3,13 @@
 %
 % Adapted from the old python.sty, mostly written by Fred Drake,
 % by Georg Brandl.
-%
+% This has now grown to become a full-fledged LaTeX support, split
+% among multiple files, some of which provide features unavailable
+% from usual LaTeX packages in interaction with the mark-up produced
+% by the Sphinx LaTeX writer.
 
 \NeedsTeXFormat{LaTeX2e}[1995/12/01]
-\ProvidesPackage{sphinx}[2023/03/19 v6.2.0 LaTeX package (Sphinx markup)]
+\ProvidesPackage{sphinx}[2024/07/01 v7.4.0 Sphinx LaTeX package (sphinx-doc)]
 
 % provides \ltx@ifundefined
 % (many packages load ltxcmds: graphicx does for pdftex and lualatex but
@@ -48,12 +51,6 @@
                          }}%
   \fi
 }
-\@namedef{sphinx_buildwarning_coloursyntax}{%
-   The colours whose definition used xcolor syntax were set to white
-   as xcolor was not found; check the latex log warnings for details}
-\@namedef{sphinx_buildwarning_colorblend}{%
-   Command \string\sphinxcolorblend\space seen but ignored in tables
-   as xcolor was not found; check the latex log warnings for details}
 \@namedef{sphinx_buildwarning_badtitlesec}{%
    Your system has titlesec version 2.10.1 which causes disappearance
    of section numbers; check the latex log warning for details}
@@ -63,29 +60,29 @@
 \@namedef{sphinx_buildwarning_badfootnotes}{%
    Footnote rendering may have had problems, due to extra package or
    document class; check latex log for instructions}%
-
+\@namedef{sphinx_buildwarning_fontawesome5ismissing}{%
+   As fontawesome5 LaTeX package is not found, admonition titles
+   default to not using icons; check div.note\string_title-icon and
+   similar options for how to configure your own.}
 
 %% OPTION HANDLING
 %
-
 % We generally first handle options then load packages, but we need
-% \definecolor from xcolor/color to handle the options.
+% \definecolor and \colorlet from xcolor to handle the options.
 
+% Support for colour options
+% --------------------------
+% At 7.4.0, package xcolor is required (which has allowed to get rid of
+% annoying fall-back branches).  Internals here got refactored to some extent.
+%
 % MEMO: xcolor \fcolorbox coloured boxes render better in some PDF viewers
 % than with color package \fcolorbox.  Since 1.6.3, Sphinx uses only its own
 % custom variant of \fcolorbox when handling code-blocks.  But \fcolorbox
-% appears also in Pygmentize output mark-up.  Also, since 5.3.0, 'sphinxsetup'
-% color options get a richer input syntax if Sphinx knows xcolor is loaded,
-% and the \sphinxcolorblend (for tables) is made available only if xcolor is
-% loaded.
-\IfFileExists{xcolor.sty}{
+% appears also in Pygmentize output mark-up.
 % Should Sphinx load xcolor with its dvipsnames and svgnames options?
-    \RequirePackage{xcolor}
-}{
-    \RequirePackage{color}
-}
+\RequirePackage{xcolor}
 
-% the \colorlet of xcolor (if at all loaded) is overkill for most internal use
+% the \colorlet of xcolor is overkill for our internal usage here
 \newcommand{\sphinxcolorlet}[2]
     {\expandafter\let\csname\@backslashchar color@#1\expandafter\endcsname
                      \csname\@backslashchar color@#2\endcsname }
@@ -93,6 +90,8 @@
 % (5.3.0) Allow colour options to use both the \definecolor and the \colorlet
 % syntaxes, for example VerbatimColor={gray}{0.9} or VerbatimColor=red!10
 % In the latter case we need the real \colorlet from xcolor package.
+% Prior to 7.4.0 xcolor was not required and thus \spx@colorlet was configured
+% to raise a warning in case of absence of xcolor.
 \def\spx@defineorletcolor#1{%
     \def\spx@definedcolor{{#1}}%
     \futurelet\spx@token\spx@defineorlet}
@@ -101,21 +100,17 @@
     \expandafter\spx@definecolor\else\expandafter\spx@colorlet\fi}
 \def\spx@colorlet#1\relax{\expandafter\colorlet\spx@definedcolor{#1}}
 \def\spx@definecolor{\expandafter\definecolor\spx@definedcolor}
-%
-\@ifpackageloaded{xcolor}%
-   {}%
-   {% xcolor not loaded because it was not found in the LaTeX installation
-\def\spx@colorlet#1\relax{%
-    \sphinxbuildwarning{coloursyntax}%
-    \PackageWarning{sphinx}{%
-Sorry, the #1 syntax requires package xcolor,\MessageBreak
-which was not found on your TeX/LaTeX installation.\MessageBreak
-\@spaces\expandafter\@firstofone\spx@definedcolor\MessageBreak
-will be set to white}%
-    \expandafter\definecolor\spx@definedcolor{rgb}{1,1,1}%
-    }% end of redefinition of \spx@colorlet
-   }% end of xcolor not found branch
-
+% These internals refactored at 7.4.0:
+\newcommand*{\spx@DeclareColorOption}[3][]{%
+% #1 = almost always "sphinx" but left empty for a few
+% #2 = option name, but internal colour name is #1#2 (i.e. with prefix)
+% #3 = initial default colour with either \definecolor or \colorlet syntax
+   % set the initial default
+   \spx@defineorletcolor{#1#2}#3\relax
+   % set the key handler to accept both \definecolor and \colorlet syntax
+   % the key name does not have the #1 prefix from the colour name
+   \define@key{sphinx}{#2}{\spx@defineorletcolor{#1#2}##1\relax}%
+}%
 
 % Handle options via "kvoptions" (later loaded by hyperref anyhow)
 \RequirePackage{kvoptions}
@@ -159,10 +154,15 @@ will be set to white}%
 \define@key{sphinx}{bookmarksdepth}{\AtBeginDocument{\hypersetup{bookmarksdepth=#1}}}
 \AtBeginDocument{\define@key{sphinx}{bookmarksdepth}{\hypersetup{bookmarksdepth=#1}}}
 % \DeclareBoolOption[false]{usespart}% not used
+
+% Code-blocks
+% -----------
+%
 % INFO: the keys for padding and border widths were extended at 5.1.0,
 % and legacy names for user interface were kept, but their definitions
 % are delayed further down.  The legacy internally used dimen registers
 % \sphinxverbatimborder and \sphinxverbatimsep got removed at 6.2.0.
+% More code-blocks related options are found in "CSS" part below.
 \DeclareBoolOption[true]{verbatimwithframe}
 \DeclareBoolOption[true]{verbatimwrapslines}
 \DeclareBoolOption[false]{verbatimforcewraps}
@@ -180,70 +180,49 @@ will be set to white}%
 \DeclareStringOption % must use braces to hide the brackets
   [{\makebox[2\fontcharwd\font`\x][r]{\textcolor{red}{\tiny$\m@th\hookrightarrow$}}}]%
   {verbatimcontinued}
-% topic boxes
+
+% Topic boxes
+% -----------
 %
 % 5.1.0 added new keys for configuration.  The legacy keys shadowsep,
-% shadowsize, shadowrule were kept for backward compatibility.  Unfortunately
-% this had bugs due to typos, which got fixed later at 6.1.2.
+% shadowsize, shadowrule were kept for backward compatibility.
+% 5.1.2 fixed some bugs.
 %
 % All configuration is now to be found in the "CSS" section below.
 %
-% \sphinxshadowsep, \sphinxshadowsize, \sphinxshadowrule \dimen registers
-% became at 5.1.0 either no-op or, for the latter, were used under an aliased
-% name.  They got removed at 6.2.0.
-%
-% notices/admonitions
-%
-% 5.1.0 added much customizability to warning, caution, attention, danger and
-% error types of notices via an enhanced sphinxheavybox environment.
-%
-% 6.2.0 added the possibility to use the same kind of rendering also for
-% note, hint, important, and tip.
-%
-% Legacy user interface for options was kept working.  All of it is handled in
-% the "CSS" section below.
-%
-% These 6.2.0 added booleans serve internally.  There is no reason for user to
-% know about them, except if it is desired to toggle mid-way in the document
-% whether note, hint, important, and tip should use the "lightbox" or the
-% "heavybox" rendering.
-\DeclareBoolOption[false]{heavynote}
-\DeclareBoolOption[false]{heavyhint}
-\DeclareBoolOption[false]{heavyimportant}
-\DeclareBoolOption[false]{heavytip}
-% footnotes
+% 6.2.0 removed \sphinxshadowsep, \sphinxshadowsize, \sphinxshadowrule
+% \dimen registers
+
+% Footnotes
+% ---------
 \DeclareStringOption[\mbox{ }]{AtStartFootnote}
 % we need a public macro name for direct use in latex file
 \newcommand*{\sphinxAtStartFootnote}{\spx@opt@AtStartFootnote}
 % no such need for this one, as it is used inside other macros
 \DeclareStringOption[\leavevmode\unskip]{BeforeFootnote}
-% some font styling.
+
+% Some font styling
+% -----------------
+% TODO: the replacement of old syntax \py@HeaderFamily as used
+% in sphinxlatexstyle{page,headings}.sty and sphinx{manual,howto}.cls
+% has never been really put in place.  Hence this isolated tidbit here.
 \DeclareStringOption[\sffamily\bfseries]{HeaderFamily}
-% colours
-% same problems as for dimensions: we want the key handler to use \definecolor.
-% first, some colours with no prefix, for backward compatibility
-\newcommand*{\sphinxDeclareColorOption}[2]{%
-   % set the initial default; only \definecolor syntax for defaults!
-   \definecolor{#1}#2%
-   % set the key handler to accept both \definecolor and \colorlet syntax
-   \define@key{sphinx}{#1}{\spx@defineorletcolor{#1}##1\relax}%
-}%
-\sphinxDeclareColorOption{TitleColor}{{rgb}{0.126,0.263,0.361}}
-\sphinxDeclareColorOption{InnerLinkColor}{{rgb}{0.208,0.374,0.486}}
-\sphinxDeclareColorOption{OuterLinkColor}{{rgb}{0.216,0.439,0.388}}
-\sphinxDeclareColorOption{VerbatimColor}{{gray}{0.95}}
-\sphinxDeclareColorOption{VerbatimBorderColor}{{RGB}{32,32,32}}
-% all other colours will be named with a "sphinx" prefix
-\newcommand*{\sphinxDeclareSphinxColorOption}[2]{%
-   % set the initial default; only \definecolor syntax for defaults!
-   \definecolor{sphinx#1}#2%
-   % set the key handler to accept both \definecolor and \colorlet syntax
-   \define@key{sphinx}{#1}{\spx@defineorletcolor{sphinx#1}##1\relax}%
-}%
-% table row colors
-\sphinxDeclareSphinxColorOption{TableRowColorHeader}{{gray}{0.86}}
-\sphinxDeclareSphinxColorOption{TableRowColorOdd}{{gray}{0.92}}
-\sphinxDeclareSphinxColorOption{TableRowColorEven}{{gray}{0.98}}
+
+% Some legacy colour options
+% --------------------------
+%
+\spx@DeclareColorOption{TitleColor}{{rgb}{0.126,0.263,0.361}}
+\spx@DeclareColorOption{InnerLinkColor}{{rgb}{0.208,0.374,0.486}}
+\spx@DeclareColorOption{OuterLinkColor}{{rgb}{0.216,0.439,0.388}}
+\spx@DeclareColorOption{VerbatimColor}{{RGB}{242,242,242}}% same as {gray}{0.95}
+\spx@DeclareColorOption{VerbatimBorderColor}{{RGB}{32,32,32}}
+% All other colours will be internally assigned a "sphinx" prefix
+
+% Table row colors
+% ----------------
+\spx@DeclareColorOption[sphinx]{TableRowColorHeader}{{gray}{0.86}}
+\spx@DeclareColorOption[sphinx]{TableRowColorOdd}{{gray}{0.92}}
+\spx@DeclareColorOption[sphinx]{TableRowColorEven}{{gray}{0.98}}
 % if not set, the "Merge" colour will keep in sync with the "Row" colour
 \def\sphinxTableMergeColorHeader{sphinxTableRowColorHeader}
 \define@key{sphinx}{TableMergeColorHeader}{%
@@ -261,37 +240,62 @@ will be set to white}%
     \def\sphinxTableMergeColorEven{sphinxTableMergeColorEven}%
 }%
 % Default color chosen to be as in minted.sty LaTeX package!
-\sphinxDeclareSphinxColorOption{VerbatimHighlightColor}{{rgb}{0.878,1,1}}
-% admonition boxes, "light" style
-% border color defaults to black
-% at 6.2.0 also background color is possible, but it then triggers
-% usage of the "sphinxheavybox" from sphinxlatexadmonitions.sty.
-\sphinxDeclareSphinxColorOption{noteBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{hintBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{importantBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{tipBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{noteBgColor}{{rgb}{1,1,1}}
-\sphinxDeclareSphinxColorOption{hintBgColor}{{rgb}{1,1,1}}
-\sphinxDeclareSphinxColorOption{importantBgColor}{{rgb}{1,1,1}}
-\sphinxDeclareSphinxColorOption{tipBgColor}{{rgb}{1,1,1}}
-% admonition boxes, "heavy" style
-% border color defaults to black and background color to white
-% As long as the color are not explicitly set via user options,
-% the sphinxpackageboxes.sty code will actually not use them anyhow.
-\sphinxDeclareSphinxColorOption{warningBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{cautionBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{attentionBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{dangerBorderColor}{{rgb}{0,0,0}}
-\sphinxDeclareSphinxColorOption{errorBorderColor}{{rgb}{0,0,0}}
-% BgColor should have been from the start BackgroundColor for better
-% match with CSS property names, but this is legacy interface
-% which is too late to change because the internal color names
-% and not only the option names have been documented at user level.
-\sphinxDeclareSphinxColorOption{warningBgColor}{{rgb}{1,1,1}}
-\sphinxDeclareSphinxColorOption{cautionBgColor}{{rgb}{1,1,1}}
-\sphinxDeclareSphinxColorOption{attentionBgColor}{{rgb}{1,1,1}}
-\sphinxDeclareSphinxColorOption{dangerBgColor}{{rgb}{1,1,1}}
-\sphinxDeclareSphinxColorOption{errorBgColor}{{rgb}{1,1,1}}
+\spx@DeclareColorOption[sphinx]{VerbatimHighlightColor}{{rgb}{0.878,1,1}}
+
+% Notices/admonitions
+% -------------------
+%
+% 5.1.0 added much customizability to warning, caution, attention, danger and
+% error types of notices via an enhanced sphinxheavybox environment.
+%
+% 6.2.0 added the possibility to use the same kind of rendering also for
+% note, hint, important, and tip.
+%
+% Legacy user interface for options was kept working.  All of it is handled in
+% the "CSS" section below.
+%
+% 6.2.0 added booleans to serve internally as a record of whether the
+% note, hint, important and tip admonitions used the legacy "lightbox" or
+% the then enhanced "heavybox" environment.
+%
+% 7.4.0 uses "heavybox" environment from sphinxlatexadmonitions in all cases,
+% hence the booleans mentioned above have been removed as well as the rather
+% complex TeX code which was done so that these booleans were made true if
+% and only if the CSS-named keys had been made usage of via 'sphinxsetup'.
+%
+% The "light style" implemented in sphinxlatexadmonitions.sty as
+% "sphinxlightbox" is not used.  Also, admonitions by default have a "title
+% row", and the corresponding options are only named in the CSS style which is
+% implemented further below.  Here we define options having a legacy name.
+%
+% seealso directive is also using "heavybox" at 7.4.0 acquiring the same
+% customizability as admonitions.
+\definecolor{sphinx-admonition-bgcolor}      {RGB}{247, 247, 247}% #F7F7F7
+\definecolor{sphinx-admonition-bordercolor}  {RGB}{134, 152, 155}% #86989B
+\definecolor{sphinx-warning-bordercolor}     {RGB}{148, 0, 0}%     #940000
+\spx@DeclareColorOption[sphinx]{noteBorderColor}     {sphinx-admonition-bordercolor}
+\spx@DeclareColorOption[sphinx]{hintBorderColor}     {sphinx-admonition-bordercolor}
+\spx@DeclareColorOption[sphinx]{importantBorderColor}{sphinx-admonition-bordercolor}
+\spx@DeclareColorOption[sphinx]{tipBorderColor}      {sphinx-admonition-bordercolor}
+\spx@DeclareColorOption[sphinx]{seealsoBorderColor}  {sphinx-admonition-bordercolor}% 7.4.0
+%
+\spx@DeclareColorOption[sphinx]{noteBgColor}     {sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{hintBgColor}     {sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{importantBgColor}{sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{tipBgColor}      {sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{seealsoBgColor}  {sphinx-admonition-bgcolor}% 7.4.0
+%
+\spx@DeclareColorOption[sphinx]{warningBorderColor}  {sphinx-warning-bordercolor}
+\spx@DeclareColorOption[sphinx]{cautionBorderColor}  {sphinx-warning-bordercolor}
+\spx@DeclareColorOption[sphinx]{attentionBorderColor}{sphinx-warning-bordercolor}
+\spx@DeclareColorOption[sphinx]{dangerBorderColor}   {sphinx-warning-bordercolor}
+\spx@DeclareColorOption[sphinx]{errorBorderColor}    {red}
+%
+\spx@DeclareColorOption[sphinx]{warningBgColor}  {sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{cautionBgColor}  {sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{attentionBgColor}{sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{dangerBgColor}   {sphinx-admonition-bgcolor}
+\spx@DeclareColorOption[sphinx]{errorBgColor}    {sphinx-admonition-bgcolor}
 %%%%%%%%
 %
 % Additions of CSS-like keys at 5.1.0 (and possibility of rounded boxes)
@@ -324,14 +328,24 @@ will be set to white}%
 % finally been removed entirely.  No more \dimen register is used here only
 % storage in macros.
 %
+% Restyling at 7.4.0 with new defaults for all admonition types
+% -------------------------------------------------------------
+%
+% So far the 5.1.0 added possibilities for fancier boxes had been used by
+% default only for code-blocks, admonitions kept their old-fashioned
+% legacy styles.  At 7.4.0, as a follow-up to the revamped styles of
+% admonitions in the HTML sphinx13 theme (PR #12439), it is decided to
+% apply similar styling for PDF output.  Also the seealso directive
+% is handled as an admonition with the same customizability.
+%
 \def\spxstring@none{none}
 \def\spxstring@clone{clone}
 %
 % Border keys
-%
+% At 7.4.0 refactoring to avoid defining legacy \spx@<type>@border
+% macros which are used nowhere, only @top, @right, @bottom, @left.
 \def\spx@tempa#1{% #1 = macro prefix
   \expandafter\spx@tempb
-  \csname #1border\expandafter\endcsname
   \csname #1border@top\expandafter\endcsname
   \csname #1border@right\expandafter\endcsname
   \csname #1border@bottom\expandafter\endcsname
@@ -340,20 +354,20 @@ will be set to white}%
   \csname #1border@opentrue\expandafter\endcsname
   \csname #1border@openfalse\endcsname
 }%
-\def\spx@tempb #1#2#3#4#5#6#7#8#9{% #9 = option prefix
-  \define@key{sphinx}{#9border-top-width}{\def#2{##1}}%
-  \define@key{sphinx}{#9border-right-width}{\def#3{##1}}%
-  \define@key{sphinx}{#9border-bottom-width}{\def#4{##1}}%
-  \define@key{sphinx}{#9border-left-width}{\def#5{##1}}%
-  \define@key{sphinx}{#9border-width}{%
-    \def#1{##1}% MEMO: not immediately expanded, should this be changed?
-    \def#2{#1}\let#3#2\let#4#2\let#5#2%
+\def\spx@tempb #1#2#3#4#5#6#7#8{% #8 = option prefix
+  \define@key{sphinx}{#8border-top-width}{\def#1{##1}}%
+  \define@key{sphinx}{#8border-right-width}{\def#2{##1}}%
+  \define@key{sphinx}{#8border-bottom-width}{\def#3{##1}}%
+  \define@key{sphinx}{#8border-left-width}{\def#4{##1}}%
+  \define@key{sphinx}{#8border-width}{%
+    % MEMO: not immediately expanded, should this be changed?
+    \def#1{##1}\let#2#1\let#3#1\let#4#1%
     }%
-  \newif#6%
-  \define@key{sphinx}{#9box-decoration-break}%
+  \newif#5%
+  \define@key{sphinx}{#8box-decoration-break}%
            {\begingroup\edef\spx@tempa{##1}\expandafter\endgroup
-            \ifx\spx@tempa\spxstring@clone#8\else#7\fi}%
-  \spx@tempc{#9}% option prefix
+            \ifx\spx@tempa\spxstring@clone#7\else#6\fi}%
+  \spx@tempc{#8}% option prefix
 }
 \def\spx@tempc #1#2{% #1 = option prefix, #2 = legacy option name
   % keep legacy option names as aliases to new-named options
@@ -362,77 +376,69 @@ will be set to white}%
   % init border-width (fetches next argument)
   \csname KV@sphinx@#1border-width\endcsname
 }
-% MEMO: prior to 6.2.0 the \fboxrule value (0.4pt, a priori) was frozen here via
-% a \dimen assignment done immediately. Now it remains \fboxrule until being used.
+% MEMO: from 6.2.0 to 7.4.0 (excluive) \fboxrule was used in the first
+% two, and was resolved only at location of use.  At 7.4.0, we again
+% use 0.4pt rather which is its default.
 %          macro prefix   option prefix   legacy option    init value
-\spx@tempa{spx@pre@}      {pre_}          {verbatimborder} \fboxrule
-\spx@tempa{spx@topic@}    {div.topic_}    {shadowrule}     \fboxrule
+\spx@tempa{spx@pre@}      {pre_}          {verbatimborder} {0.4pt}
+\spx@tempa{spx@topic@}    {div.topic_}    {shadowrule}     {0.4pt}
 \spx@tempa{spx@note@}     {div.note_}     {noteborder}     {0.5pt}
 \spx@tempa{spx@hint@}     {div.hint_}     {hintborder}     {0.5pt}
 \spx@tempa{spx@important@}{div.important_}{importantborder}{0.5pt}
 \spx@tempa{spx@tip@}      {div.tip_}      {tipborder}      {0.5pt}
-\spx@tempa{spx@warning@}  {div.warning_}  {warningborder}  {1pt}
-\spx@tempa{spx@caution@}  {div.caution_}  {cautionborder}  {1pt}
-\spx@tempa{spx@attention@}{div.attention_}{attentionborder}{1pt}
-\spx@tempa{spx@danger@}   {div.danger_}   {dangerborder}   {1pt}
-\spx@tempa{spx@error@}    {div.error_}    {errorborder}    {1pt}
+\spx@tempa{spx@seealso@}  {div.seealso_}  {seealsoborder}  {0.5pt}% new at 7.4.0
+\spx@tempa{spx@warning@}  {div.warning_}  {warningborder}  {1.5pt}% mod. at 7.4.0
+\spx@tempa{spx@caution@}  {div.caution_}  {cautionborder}  {1.5pt}% mod. at 7.4.0
+\spx@tempa{spx@attention@}{div.attention_}{attentionborder}{1.5pt}% mod. at 7.4.0
+\spx@tempa{spx@danger@}   {div.danger_}   {dangerborder}   {1.5pt}% mod. at 7.4.0
+\spx@tempa{spx@error@}    {div.error_}    {errorborder}    {2pt}  % mod. at 7.4.0
 % this one new at 6.2.0: (we do not create a "legacy name" for it)
-\spx@tempa{spx@box@}      {box_}          {box_border-width}\fboxrule
+\spx@tempa{spx@box@}      {box_}          {box_border-width}{0.4pt}
 % Set default box-decoration-break style for codeblocks to slice
 \spx@pre@border@opentrue % new default at 6.0.0: slice, not clone
 % 6.2.0 has added support for box-decoration-break=slice to all
 % other directives, formerly the option setting was ignored for them.
 
 % Padding keys
-%
+% At 7.4.0, \spx@<type>@padding internal macros removed, only @top, @right,
+% @bottom, @left are actually needed by sphinxpackageboxes.sty.
 \def\spx@tempa#1{%
   \expandafter\spx@tempb
-  \csname #1padding\expandafter\endcsname
   \csname #1padding@top\expandafter\endcsname
   \csname #1padding@right\expandafter\endcsname
   \csname #1padding@bottom\expandafter\endcsname
   \csname #1padding@left\endcsname
 }%
-\def\spx@tempb #1#2#3#4#5#6{% #6 = option prefix
-  \define@key{sphinx}{#6padding-top}{\def#2{##1}}%
-  \define@key{sphinx}{#6padding-right}{\def#3{##1}}%
-  \define@key{sphinx}{#6padding-bottom}{\def#4{##1}}%
-  \define@key{sphinx}{#6padding-left}{\def#5{##1}}%
-  \define@key{sphinx}{#6padding}{%
-     \def#1{##1}%
-     \def#2{#1}\let#3#2\let#4#2\let#5#2%
+\def\spx@tempb #1#2#3#4#5#6#7#8#9{% #5 = option prefix
+  \define@key{sphinx}{#5padding-top}{\def#1{##1}}%
+  \define@key{sphinx}{#5padding-right}{\def#2{##1}}%
+  \define@key{sphinx}{#5padding-bottom}{\def#3{##1}}%
+  \define@key{sphinx}{#5padding-left}{\def#4{##1}}%
+  \define@key{sphinx}{#5padding}{%
+     \def#1{##1}\let#2#1\let#3#1\let#4#1%
   }%
-  % initialization (will fetch "init" argument next):
-  \csname KV@sphinx@#6padding\endcsname
+  % initial defaults
+  \def#1{#6}\def#2{#7}\def#3{#8}\def#4{#9}%
 }
 % MEMO: prior to 6.2.0 the \fboxsep value (3pt, a priori) was frozen here via
-% a \dimen assignment done immediately. Now it remains \fboxsep until being used.
-%         #1 macro prefix #6 option prefix  init value
-\spx@tempa{spx@pre@}      {pre_}            \fboxsep
-\spx@tempa{spx@topic@}    {div.topic_}      {5pt}
-% MEMO: prior to 6.2.0, "note" type admonitions used sphinxlightbox automatically
-% and had no interface to set the padding parameters needed by sphinxheavybox.
-% At 6.2.0 they acquired such interface and the default is set as for legacy
-% default of "warning" type.  I hesitated using \fboxsep, but if I did I would
-% then need to explain how to change "note etc..." into behaving exactly
-% as "warning etc...", which goes via the \dimexpr here which is too scary to
-% put sanely into documentation.
-\spx@tempa{spx@note@}     {div.note_}       {\dimexpr.6\baselineskip-\spx@note@border\relax}
-\spx@tempa{spx@hint@}     {div.hint_}       {\dimexpr.6\baselineskip-\spx@hint@border\relax}
-\spx@tempa{spx@important@}{div.important_}  {\dimexpr.6\baselineskip-\spx@important@border\relax}
-\spx@tempa{spx@tip@}      {div.tip_}        {\dimexpr.6\baselineskip-\spx@tip@border\relax}
-% MEMO: prior to 5.1.0 padding was not separately customizable from border
-% width for warning type admonitions.  The below keeps the legacy behavior of a
-% constant borderwidth+padding.  The dim expression is not evaluated yet, only
-% at time of use (so that it dynamically adapts to the border width setting).
-% MEMO: I could use everywhere \spx@notice@border, as sphinxadmonition environment
-% configures it to hold the \spx@<type>@border value.
-\spx@tempa{spx@warning@}  {div.warning_}    {\dimexpr.6\baselineskip-\spx@warning@border\relax}
-\spx@tempa{spx@caution@}  {div.caution_}    {\dimexpr.6\baselineskip-\spx@caution@border\relax}
-\spx@tempa{spx@attention@}{div.attention_}  {\dimexpr.6\baselineskip-\spx@attention@border\relax}
-\spx@tempa{spx@danger@}   {div.danger_}     {\dimexpr.6\baselineskip-\spx@danger@border\relax}
-\spx@tempa{spx@error@}    {div.error_}      {\dimexpr.6\baselineskip-\spx@error@border\relax}
-\spx@tempa{spx@box@}      {box_}            \fboxsep
+% a \dimen assignment done immediately. From 6.2.0 to 7.4.0 an unfrozen
+% \fboxsep was used, and at 7.4.0 it is again explicit 3pt.
+% The defaults for admonitions were all modified at 7.4.0.
+%         #1 macro prefix #6 option prefix   top right bottom left
+\spx@tempa{spx@pre@}      {pre_}            {3pt}{3pt}{3pt}{3pt}
+\spx@tempa{spx@topic@}    {div.topic_}      {10pt}{12pt}{12pt}{12pt}
+% 7.4.0 drops legacy settings which linked strangely padding with border width
+\spx@tempa{spx@note@}     {div.note_}       {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@hint@}     {div.hint_}       {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@important@}{div.important_}  {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@tip@}      {div.tip_}        {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@seealso@}  {div.seealso_}    {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@warning@}  {div.warning_}    {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@caution@}  {div.caution_}    {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@attention@}{div.attention_}  {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@danger@}   {div.danger_}     {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@error@}    {div.error_}      {6pt}{12pt}{6pt}{12pt}
+\spx@tempa{spx@box@}      {box_}            {3pt}{3pt}{3pt}{3pt}
 % define legacy verbatimsep key as alias of pre_padding key
 \expandafter\let\expandafter\KV@sphinx@verbatimsep\csname KV@sphinx@pre_padding\endcsname
 % define legacy shadowsep key as alias of div.topic_padding key
@@ -450,30 +456,32 @@ will be set to white}%
   \csname #1radius@bottomright\expandafter\endcsname
   \csname #1radius@bottomleft\endcsname
 }%
-\def\spx@tempb #1#2#3#4#5{% #5 = option prefix
+\def\spx@tempb #1#2#3#4#5#6#7#8#9{% #5 = option prefix
   \define@key{sphinx}{#5border-top-left-radius}{\def#1{##1}}%
   \define@key{sphinx}{#5border-top-right-radius}{\def#2{##1}}%
   \define@key{sphinx}{#5border-bottom-right-radius}{\def#3{##1}}%
   \define@key{sphinx}{#5border-bottom-left-radius}{\def#4{##1}}%
   \define@key{sphinx}{#5border-radius}{\def#1{##1}\let#2#1\let#3#1\let#4#1}%
-  \csname KV@sphinx@#5border-radius\endcsname % fetches next argument
+  \def#1{#6}\def#2{#7}\def#3{#8}\def#4{#9}%
 }
 % The init value for corner radius in code-blocks was \z@ (i.e. 0pt) prior
-% to 6.0.0., then 3pt, then \fboxsep at 6.2.0 as padding is \fboxsep,
-% and \fboxsep=3pt per default (also with platex).
-%          macro prefix    option prefix     init value
-\spx@tempa{spx@pre@}      {pre_}            \fboxsep
-\spx@tempa{spx@topic@}    {div.topic_}      \z@
-\spx@tempa{spx@note@}     {div.note_}       \z@
-\spx@tempa{spx@hint@}     {div.hint_}       \z@
-\spx@tempa{spx@important@}{div.important_}  \z@
-\spx@tempa{spx@tip@}      {div.tip_}        \z@
-\spx@tempa{spx@warning@}  {div.warning_}    \z@
-\spx@tempa{spx@caution@}  {div.caution_}    \z@
-\spx@tempa{spx@attention@}{div.attention_}  \z@
-\spx@tempa{spx@danger@}   {div.danger_}     \z@
-\spx@tempa{spx@error@}    {div.error_}      \z@
-\spx@tempa{spx@box@}      {box_}            \fboxsep
+% to 6.0.0., then 3pt, then \fboxsep at 6.2.0 as padding was also \fboxsep.
+% At 7.4.0 the 3pt is used (which is normal value of \fboxsep).
+% At 7.4.0 some admonitions use rounded corners as well.
+%          macro prefix    option prefix     tl   tr   br   bl
+\spx@tempa{spx@pre@}      {pre_}            {3pt}{3pt}{3pt}{3pt}
+\spx@tempa{spx@topic@}    {div.topic_}      \z@  \z@  {12pt} \z@
+\spx@tempa{spx@note@}     {div.note_}       {5pt}{5pt}{5pt}{5pt}
+\spx@tempa{spx@hint@}     {div.hint_}       {5pt}{5pt}{5pt}{5pt}
+\spx@tempa{spx@important@}{div.important_}  \z@\z@\z@\z@
+\spx@tempa{spx@tip@}      {div.tip_}        {5pt}{5pt}{5pt}{5pt}
+\spx@tempa{spx@seealso@}  {div.seealso_}    \z@\z@\z@\z@
+\spx@tempa{spx@warning@}  {div.warning_}    \z@\z@\z@\z@
+\spx@tempa{spx@caution@}  {div.caution_}    \z@\z@\z@\z@
+\spx@tempa{spx@attention@}{div.attention_}  \z@\z@\z@\z@
+\spx@tempa{spx@danger@}   {div.danger_}     \z@\z@\z@\z@
+\spx@tempa{spx@error@}    {div.error_}      \z@\z@\z@\z@
+\spx@tempa{spx@box@}      {box_}            {3pt}{3pt}{3pt}{3pt}
 
 % Shadow keys
 %
@@ -494,6 +502,7 @@ will be set to white}%
 \spx@tempa{spx@hint@}
 \spx@tempa{spx@important@}
 \spx@tempa{spx@tip@}
+\spx@tempa{spx@seealso@}% 7.4.0
 \spx@tempa{spx@warning@}
 \spx@tempa{spx@caution@}
 \spx@tempa{spx@attention@}
@@ -541,6 +550,7 @@ will be set to white}%
 \spx@tempa{spx@hint@}     {div.hint_}
 \spx@tempa{spx@important@}{div.important_}
 \spx@tempa{spx@tip@}      {div.tip_}
+\spx@tempa{spx@seealso@}  {div.seealso_}
 \spx@tempa{spx@warning@}  {div.warning_}
 \spx@tempa{spx@caution@}  {div.caution_}
 \spx@tempa{spx@attention@}{div.attention_}
@@ -564,8 +574,9 @@ will be set to white}%
   \fi
 }%
 
-% Color keys
-% (four of them: border, background, shadow and the text color)
+% Color keys, TeXextras key, keys for admonition titles with icon
+%
+% Historical remarks to be removed at some point:
 %
 % Some problems due to legacy naming scheme which had diverging conventions
 % for code-blocks (VerbatimBorderColor, VerbatimColor) and admonitions
@@ -574,27 +585,31 @@ will be set to white}%
 % example sphinxwarningBgColor are also documented at user level, they are not
 % only internally used.
 %
-% For topic directive, "legacy" (by this I mean Sphinx around 2016-2017 after
-% my first additions to LaTeX) had no interface for colors, so I could change
-% some internals with no breakage during 5.x up to 6.2.0.  So topic
-% (shadowbox) could be unified with admonitions (sphinxheavybox), and the
-% "set-up" macros could all be moved into a single one in the
-% sphinxpackageboxes.sty file, with only one argument holding the directive
-% type.
+% For topic directive, "legacy" (around 2016-2017) had no interface for
+% colors, so some internals could be changed with no breakage during 5.x up to
+% 6.2.0.  For example topic (shadowbox) could be unified with admonitions
+% (sphinxheavybox), and the "set-up" macros could all be moved into a single
+% one in the sphinxpackageboxes.sty file, with only one argument holding the
+% directive type.
 %
 % It was then needed only for sphinxlatexliterals.sty to let its
 % \spx@verb@boxes@fcolorbox@setup incorporate some extra adjustment.
 %
-% We associate a boolean to each color, so that the box code can
-% decide to insert a \color command or consider it is not needed.
+% 7.4.0 removes usages of booleans relative to usage of a colour for
+% background or border which were there to optimize the boxing code from
+% sphinxpackageboxes.sty when colours where not needed.  These were internal
+% macros so their removal should not be considered breaking.
+% We keep the infrastructure for "shadowcolor" and "textcolor" because the
+% defaults for them remain not to have specific colour.
+%
+% 7.4.0 adds keys for admonition titles: for background and foreground colors,
+% and for icons (whose defaults are picked from Free Fontawasome 5).
 \def\spx@tempa#1{%
   \expandafter\spx@tempb
   \csname if#1withshadowcolor\expandafter\endcsname
-  \csname if#1withbordercolor\expandafter\endcsname
-  \csname if#1withbackgroundcolor\expandafter\endcsname
   \csname if#1withtextcolor\endcsname
 }%
-\def\spx@tempb#1#2#3#4{\newif#1\newif#2\newif#3\newif#4}%
+\def\spx@tempb#1#2{\newif#1\newif#2}%
 %          macro prefix
 \spx@tempa{spx@pre@}
 \spx@tempa{spx@topic@}
@@ -602,6 +617,7 @@ will be set to white}%
 \spx@tempa{spx@hint@}
 \spx@tempa{spx@important@}
 \spx@tempa{spx@tip@}
+\spx@tempa{spx@seealso@}
 \spx@tempa{spx@warning@}
 \spx@tempa{spx@caution@}
 \spx@tempa{spx@attention@}
@@ -611,29 +627,36 @@ will be set to white}%
 %
 \def\spx@tempa#1{% #1 = macro prefix
   \expandafter\spx@tempb
-  \csname #1withbordercolortrue\expandafter\endcsname
-  \csname #1withbackgroundcolortrue\expandafter\endcsname
   \csname #1withshadowcolortrue\expandafter\endcsname
-  \csname #1withtextcolortrue\endcsname
+  \csname #1withtextcolortrue\expandafter\endcsname
+  \csname #1TeXextras\endcsname
 }
-\def\spx@tempb#1#2#3#4#5#6{% #5 = option prefix, #6 = color name prefix
-  \define@key{sphinx}{#5border-TeXcolor}%
-     {#1\spx@defineorletcolor{#6BorderColor}##1\relax}%
-  \define@key{sphinx}{#5background-TeXcolor}%
-     {#2\spx@defineorletcolor{#6BgColor}##1\relax}%
-  \define@key{sphinx}{#5box-shadow-TeXcolor}%
-     {#3\spx@defineorletcolor{#6ShadowColor}##1\relax}%
-  \define@key{sphinx}{#5TeXcolor}%
-     {#4\spx@defineorletcolor{#6TextColor}##1\relax}%
+% 7.4.0 adds options for a title.  They have an action only for admonitions,
+% and seealso.
+\def\spx@tempb#1#2#3#4#5{% #4 = option prefix, #5 = color name prefix
+  \define@key{sphinx}{#4border-TeXcolor}%
+     {\spx@defineorletcolor{#5BorderColor}##1\relax}%
+  \define@key{sphinx}{#4background-TeXcolor}%
+     {\spx@defineorletcolor{#5BgColor}##1\relax}%
+  \define@key{sphinx}{#4title-background-TeXcolor}%
+     {\spx@defineorletcolor{#5TtlBgColor}##1\relax}%
+  \define@key{sphinx}{#4title-foreground-TeXcolor}%
+     {\spx@defineorletcolor{#5TtlFgColor}##1\relax}%
+  \define@key{sphinx}{#4title-icon}%
+     {\@namedef{#5TtlIcon}{##1}}%
+  \define@key{sphinx}{#4box-shadow-TeXcolor}%
+     {#1\spx@defineorletcolor{#5ShadowColor}##1\relax}%
+  \define@key{sphinx}{#4TeXcolor}%
+     {#2\spx@defineorletcolor{#5TextColor}##1\relax}%
+  \define@key{sphinx}{#4TeXextras}%
+     {\def#3{##1}}%
 }
 %          macro prefix    option prefix    color name prefix
 \spx@tempa{spx@pre@}      {pre_}            {Verbatim}
     % (memo: internal VerbatimShadowColor was formerly sphinxVerbatimShadowColor)
     % internal legacy color name is VerbatimColor not VerbatimBgColor, so redefine:
     \define@key{sphinx}{pre_background-TeXcolor}%
-      {\spx@pre@withbackgroundcolortrue\spx@defineorletcolor{VerbatimColor}#1\relax}%
-    \spx@pre@withbordercolortrue        % 6.0.0 VerbatimBorderColor {RGB}{32,32,32}
-    \spx@pre@withbackgroundcolortrue    % 6.0.0 VerbatimColor       {gray}{0.95}
+      {\spx@defineorletcolor{VerbatimColor}#1\relax}%
     % Keep legacy option names working
     \expandafter\let\expandafter\KV@sphinx@VerbatimBorderColor
                                 \csname KV@sphinx@pre_border-TeXcolor\endcsname
@@ -646,6 +669,7 @@ will be set to white}%
 \spx@tempa{spx@hint@}     {div.hint_}       {sphinxhint}
 \spx@tempa{spx@important@}{div.important_}  {sphinximportant}
 \spx@tempa{spx@tip@}      {div.tip_}        {sphinxtip}
+\spx@tempa{spx@seealso@}  {div.seealso_}    {sphinxseealso}
 \spx@tempa{spx@warning@}  {div.warning_}    {sphinxwarning}
 \spx@tempa{spx@caution@}  {div.caution_}    {sphinxcaution}
 \spx@tempa{spx@attention@}{div.attention_}  {sphinxattention}
@@ -666,11 +690,12 @@ will be set to white}%
     \spx@tempa{div.error_}      {error}
 
     % Keep legacy sphinxsetup <type>BorderColor for <type>=note, hint, ...
-    % which will not trigger sphinxheavybox
-    % Add "legacy" hintTextColor etc... that will not trigger sphinxheavybox
+    % Add "legacy" names <type>BgColor (added at 7.4.0) and <type>TextColor
     \def\spx@tempa#1#2{% #1 = CSS like option prefix, #2 = legacy option prefix
       \expandafter\let\csname KV@sphinx@#2BorderColor\expandafter\endcsname
                       \csname KV@sphinx@#1border-TeXcolor\endcsname
+      \expandafter\let\csname KV@sphinx@#2BgColor\expandafter\endcsname
+                      \csname KV@sphinx@#1background-TeXcolor\endcsname
       \expandafter\let\csname KV@sphinx@#2TextColor\expandafter\endcsname
                       \csname KV@sphinx@#1TeXcolor\endcsname
     }
@@ -679,28 +704,7 @@ will be set to white}%
     \spx@tempa{div.important_}  {important}
     \spx@tempa{div.tip_}        {tip}
 
-% The TeXextras key
-%
-\def\spx@tempa#1{% #1 = macro prefix
-  \expandafter\spx@tempb\csname #1TeXextras\endcsname
-}
-\def\spx@tempb#1#2{% #2 = option prefix
-  \define@key{sphinx}{#2TeXextras}{\def#1{##1}}%
-}
-%          macro prefix   option prefix
-\spx@tempa{spx@pre@}      {pre_}
-\spx@tempa{spx@topic@}    {div.topic_}
-\spx@tempa{spx@note@}     {div.note_}
-\spx@tempa{spx@hint@}     {div.hint_}
-\spx@tempa{spx@important@}{div.important_}
-\spx@tempa{spx@tip@}      {div.tip_}
-\spx@tempa{spx@warning@}  {div.warning_}
-\spx@tempa{spx@caution@}  {div.caution_}
-\spx@tempa{spx@attention@}{div.attention_}
-\spx@tempa{spx@danger@}   {div.danger_}
-\spx@tempa{spx@error@}    {div.error_}
-\spx@tempa{spx@box@}      {box_}
-    % Add "legacy" hintTeXextras etc... that will not trigger sphinxheavybox
+    % Add "legacy" hintTeXextras etc... 
     \def\spx@tempa#1#2{% #1 = CSS like option prefix, #2 = legacy option prefix
       \expandafter\let\csname KV@sphinx@#2TeXextras\expandafter\endcsname
                       \csname KV@sphinx@#1TeXextras\endcsname
@@ -710,64 +714,105 @@ will be set to white}%
     \spx@tempa{div.important_}  {important}
     \spx@tempa{div.tip_}        {tip}
 
-% For note type admonitions, redefine all CSS-like named options to trigger
-% the "heavybox" path.
+    % At 7.4.0, let topic/contents boxes acquire background and border colours
+    % and give the shadow some colour other than black
+    \setkeys{sphinx}{div.topic_border-TeXcolor=sphinx-admonition-bordercolor,
+                     div.topic_background-TeXcolor=sphinx-admonition-bgcolor,
+                     div.topic_box-shadow-TeXcolor={RGB}{108,108,108},
+                   }
+
+
+% 7.4.0 lets all types of admonitions style especially their titlss.
+% The Sphinx default colours for admonition titles are copied from PR #12486
+% which modified sphinx13.css (see also earlier #12439)
+% The actual code using the colours and icons whose defaults are set here
+% is to be found in sphinxlatexadmonitions.sty.
 %
-% MEMO: the noteBorderColor and noteborder legacy options have already been
-% re-created and they do not trigger the "heavybox" as their meaning will not
-% be modified in the loop below contrarily to their CSS counterparts
-% div.note_border-TeXcolor and div.note_border-width, and to the noteBgColor
-% etc... which are handled below.
+% MEMO: unfortunately xcolor does NOT implement HSL but only HSB!
+% So the sphinx13.css colours specified via hsl() got converted to RGB here
+\definecolor{sphinx-admonition-title-bgcolor}{RGB}{229,229,229} % hsl(0, 0%, 90%);
+\definecolor{sphinx-admonition-title-fgcolor}{RGB}{127,127,127} % hsl(0, 0%, 50%);
+\definecolor{sphinx-warning-title-bgcolor}   {RGB}{248,228,210} % hsl(28.5, 74%, 90%);
+\definecolor{sphinx-warning-title-fgcolor}   {RGB}{221,122,33}  % hsl(28.5, 74%, 50%);
+\definecolor{sphinx-note-title-bgcolor}      {RGB}{208,222,250} % hsl(219.5, 84%, 90%);
+\definecolor{sphinx-note-title-fgcolor}      {RGB}{20,93,234}   % hsl(219.5, 84%, 50%);
+\definecolor{sphinx-success-title-bgcolor}   {RGB}{220,239,230} % hsl(150, 36.7%, 90%);
+\definecolor{sphinx-success-title-fgcolor}   {RGB}{81,174,128}  % hsl(150, 36.7%, 50%);
+\definecolor{sphinx-error-title-bgcolor}     {RGB}{238,220,220} % hsl(0, 37%, 90%);
+\definecolor{sphinx-error-title-fgcolor}     {RGB}{174,80,80}   % hsl(0, 37%, 50%);
+%%
+%% TODO: support todo (sic).
+%% Currently the LaTeX mark-up is
+%% \begin{sphinxadmonition}{note}{Todo:} and actually even worse
+%% \begin{sphinxadmonition}{note}{\label{some tag}Todo:} but the \label
+%% can not work correctly as there is no target from a LaTeX counter.
+%%
+%%\definecolor{sphinx-todo-title-bgcolor}    {RGB}{226,204,254} % hsl(266.8, 100%, 90%);
+%%\definecolor{sphinx-todo-title-fgcolor}    {RGB}{113,0,255}   % hsl(266.8, 100%, 50%);
+
+% The support for default icons:
+\IfFileExists{fontawesome5.sty}{%
+  \RequirePackage{fontawesome5}
+  \@namedef{sphinx-icon-pencil}{\faIcon{pencil-alt}}
+  \@namedef{sphinx-icon-question}{\faIcon{question-circle}}
+  \@namedef{sphinx-icon-info}{\faIcon{info-circle}}
+  \@namedef{sphinx-icon-flame}{\faIcon{fire-alt}}
+  \@namedef{sphinx-icon-spark}{\faIcon{radiation}}% we did not find a good match
+                                % to sphinx13.css svg spark icon in fontawesome 5 LaTeX package
+  \@namedef{sphinx-icon-warning}{\faIcon{exclamation-triangle}}
+  \@namedef{sphinx-icon-failure}{\faIcon{skull-crossbones}}% 
+                                 % but times-circle would be more alike sphinx13.css --icon-failure
+}%
+{% no fontawasome5.sty
+  \sphinxbuildwarning{fontawesome5ismissing}%
+  \PackageWarningNoLine{sphinx}{fontawesome5 not available!\MessageBreak
+    Default admonition titles will use no icons.\MessageBreak
+    Check div.note_title-icon and similar options}
+}
+
+% Now use the above colours as default settings, following the choices
+% done in sphinx13.css
+\setkeys{sphinx}{
+  div.note_title-background-TeXcolor=sphinx-note-title-bgcolor,
+  div.note_title-foreground-TeXcolor=sphinx-note-title-fgcolor,
 %
-% This goes via rather hardcore TeX here.
-\def\spx@tempa#1{\if\relax#1\expandafter\@gobble
-  \else
-    \toks@{##1}%
-    \expandafter\def\csname KV@sphinx@div.note_#1\expandafter\endcsname
-        \the\toks0\expandafter{%
-        \csname spx@opt@heavynotetrue\expandafter\expandafter\expandafter\endcsname
-        \csname KV@sphinx@div.note_#1\endcsname{##1}}%
-    \expandafter\def\csname KV@sphinx@div.hint_#1\expandafter\endcsname
-        \the\toks0\expandafter{%
-        \csname spx@opt@heavyhinttrue\expandafter\expandafter\expandafter\endcsname
-        \csname KV@sphinx@div.hint_#1\endcsname{##1}}%
-    \expandafter\def\csname KV@sphinx@div.important_#1\expandafter\endcsname
-        \the\toks0\expandafter{%
-        \csname spx@opt@heavyimportanttrue\expandafter\expandafter\expandafter\endcsname
-        \csname KV@sphinx@div.important_#1\endcsname{##1}}%
-    \expandafter\def\csname KV@sphinx@div.tip_#1\expandafter\endcsname
-        \the\toks0\expandafter{%
-        \csname spx@opt@heavytiptrue\expandafter\expandafter\expandafter\endcsname
-        \csname KV@sphinx@div.tip_#1\endcsname{##1}}%
-  \fi
-  \spx@tempa
+  div.hint_title-background-TeXcolor=sphinx-success-title-bgcolor,
+  div.hint_title-foreground-TeXcolor=sphinx-success-title-fgcolor,
+  div.tip_title-background-TeXcolor=sphinx-success-title-bgcolor,
+  div.tip_title-foreground-TeXcolor=sphinx-success-title-fgcolor,
+  div.seealso_title-background-TeXcolor=sphinx-success-title-bgcolor,
+  div.seealso_title-foreground-TeXcolor=sphinx-success-title-fgcolor,
+%
+  div.important_title-background-TeXcolor=sphinx-warning-title-bgcolor,
+  div.important_title-foreground-TeXcolor=sphinx-warning-title-fgcolor,
+  div.caution_title-background-TeXcolor=sphinx-warning-title-bgcolor,
+  div.caution_title-foreground-TeXcolor=sphinx-warning-title-fgcolor,
+  div.warning_title-background-TeXcolor=sphinx-warning-title-bgcolor,
+  div.warning_title-foreground-TeXcolor=sphinx-warning-title-fgcolor,
+%
+  div.attention_title-background-TeXcolor=sphinx-error-title-bgcolor,
+  div.attention_title-foreground-TeXcolor=sphinx-error-title-fgcolor,
+  div.danger_title-background-TeXcolor=sphinx-error-title-bgcolor,
+  div.danger_title-foreground-TeXcolor=sphinx-error-title-fgcolor,
+  div.error_title-background-TeXcolor=sphinx-error-title-bgcolor,
+  div.error_title-foreground-TeXcolor=red,
+%
+% TODO: implement todo (sic)
+%
+% Icon defaults.  These names are copied over from sphinx13.css
+% and their actual LaTeX definitions are above and emulate the svg
+% icons, if fontawesome5 was found, else they expand to do nothing.
+  div.note_title-icon=\@nameuse{sphinx-icon-pencil},
+  div.hint_title-icon=\@nameuse{sphinx-icon-question},
+  div.tip_title-icon=\@nameuse{sphinx-icon-info},
+  div.seealso_title-icon=\@nameuse{sphinx-icon-info},
+  div.important_title-icon=\@nameuse{sphinx-icon-flame},
+  div.caution_title-icon=\@nameuse{sphinx-icon-spark},
+  div.warning_title-icon=\@nameuse{sphinx-icon-warning},
+  div.attention_title-icon=\@nameuse{sphinx-icon-warning},
+  div.danger_title-icon=\@nameuse{sphinx-icon-spark},
+  div.error_title-icon=\@nameuse{sphinx-icon-failure},
 }
-\spx@tempa{border-width}%
-          {border-top-width}{border-right-width}{border-bottom-width}{border-left-width}%
-          {box-decoration-break}%
-          {padding}%
-          {padding-top}{padding-right}{padding-bottom}{padding-left}%
-          {border-radius}%
-          {border-top-left-radius}{border-top-right-radius}%
-          {border-bottom-right-radius}{border-bottom-left-radius}%
-          {box-shadow}%
-          {border-TeXcolor}{background-TeXcolor}{box-shadow-TeXcolor}{TeXcolor}%
-          {TeXextras}%
-\relax
-
-% Now we add at 6.2.0 <type>BgColor et al. options which will trigger the
-% "heavybox" as they are \let to the div.<type>_background-TeXColor option
-% which has already been enhanced to set the boolean for rendering via
-% "heavybox".  This is in contrast with legacy <type>BorderColor,
-% and with the new <type>TeXcolor and <type>TeXextras.
-    \def\spx@tempa#1#2{% #1 = CSS like option prefix, #2 = legacy style option prefix
-      \expandafter\let\csname KV@sphinx@#2BgColor\expandafter\endcsname
-                      \csname KV@sphinx@#1background-TeXcolor\endcsname
-    }
-    \spx@tempa{div.note_}       {note}
-    \spx@tempa{div.hint_}       {hint}
-    \spx@tempa{div.important_}  {important}
-    \spx@tempa{div.tip_}        {tip}
 
 \newif\ifspx@opt@box@addstrut
 \expandafter\def\csname KV@sphinx@box_addstrut\endcsname#1{%
@@ -918,20 +963,23 @@ will be set to white}%
 }
 % Some of these defaults got already set.  But we now list them all explicitly
 % for a complete initial configuration of reset storage.
-%
+% At 7.4.0, \fboxrule and \fboxsep replaced by 0.4pt and 3pt which are anyhow
+% the defaults for these LaTeX dimensions.
 \let\spx@boxes@sphinxbox@defaults\@gobble
 \sphinxboxsetup{%
-                border-width=\fboxrule,% <-not really needed to avoid EOL space
-                padding=\fboxsep,%         but done here out of habit
-                border-radius=\fboxsep,%
-                box-shadow=none,%
-% As xcolor is perhaps not loaded we can not use background-TeXcolor=VerbatimColor
-% which would not be compatible with \definecolor syntax.
-                border-TeXcolor={RGB}{32,32,32},%  the default VerbatimBorderColor
-                background-TeXcolor={gray}{0.95},% the default VerbatimColor
-                box-shadow-TeXcolor={rgb}{0,0,0},%
-                TeXextras={},%
-                addstrut=false% (a final comma here would not hurt)
+                border-width=0.4pt,
+                padding=3pt,
+                border-radius=0.4pt,
+                box-shadow=none,
+% MEMO: as xcolor is loaded, \spx@defineorletcolor has a "\colorlet" branch
+% which makes this syntax acceptable and avoids duplicating here the values.
+                border-TeXcolor=VerbatimBorderColor,
+                background-TeXcolor=VerbatimColor,
+% 7.4.0 modified the color of the shadow (anyhow box-shadow is set above to none
+% so no shadow is drawn), to be as the new shadow colour of topic boxes.
+                box-shadow-TeXcolor={RGB}{108,108,108},
+                TeXextras={},
+                addstrut=false,
                }%
 \RequirePackage{sphinxpackageboxes}
 \input{sphinxlatexadmonitions.sty}
diff --git a/sphinx/texinputs/sphinxlatexadmonitions.sty b/sphinx/texinputs/sphinxlatexadmonitions.sty
index a31ae4ce3a2..5cf69e3d5d8 100644
--- a/sphinx/texinputs/sphinxlatexadmonitions.sty
+++ b/sphinx/texinputs/sphinxlatexadmonitions.sty
@@ -1,25 +1,40 @@
 %% NOTICES AND ADMONITIONS
 %
 % change this info string if making any custom modification
-\ProvidesFile{sphinxlatexadmonitions.sty}[2023/03/19 admonitions]
+\ProvidesFile{sphinxlatexadmonitions.sty}[2024/07/01 v7.4.0 admonitions]
 
 % Provides support for this output mark-up from Sphinx latex writer:
 %
-% - sphinxseealso environment added at 6.1.0
+% - sphinxseealso environment added at 6.1.0.
+%
+%   At 7.4.0 it too now uses sphinxheavybox, and has the same
+%   associated sphinxsetup CSS keys as admonitions do.
 %
 % - sphinxadmonition (environment)
-%   This is a dispatch supporting
+%   This is a dispatch which originally configured
+%
+%   - note, hint, important, tip to use sphinxlightbox or optionnaly
+%     sphinxheavybox since 6.2.0.
+%   - warning, caution, attention, danger, error to use sphinxheavybox.
+%
+%   At 7.4.0 all admonitions use sphinxheavybox.
 %
-%   - note, hint, important, tip                 (via sphinxlightbox)
-%                    (also optionally via sphinxheavybox since 6.2.0)
-%   - warning, caution, attention, danger, error (via sphinxheavybox)
+% - all environments sphinxnote, sphinxwarning, etc... can be redefined
+%   as will by user. Thay have one parameter #1 which is the title.
 %
-%   Each sphinx<notice name> environment can be redefined by user.
-%   The defaults are customizable via various colour and dimension
-%   settings, cf sphinx docs (latex customization).
+% - all default sphinxnote, sphinxwarning, etc... use associated
+%   one-argment macros \sphinxstylenotetitle, \sphinxstylewarningtitle, 
+%   etc which can be redefined, and whose default is to use
+%   \sphinxdotitlerowwithicon to typeset the title in a coloured header
+%   row at top of the admonition. (new with 7.4.0)
+%
+% The sphinxlightbox environment is kept only for projects with LaTeX
+% code which used it via custom definitions done in preamble or
+% via raw latex directive.
 %
 % Requires:
 \RequirePackage{sphinxpackageboxes}
+% 7.4.0 removes unneeded \spx@boxes@border
 \RequirePackage{framed}% used by sphinxheavybox
 %
 % Dependencies (they do not need to be defined at time of loading):
@@ -29,25 +44,17 @@
 % - dimension register \spx@image@maxheight from sphinxlatexgraphics.sty
 %
 % - \savenotes/\spewnotes from sphinxpackagefootnote (for sphinxheavybox)
-%
-% - \sphinxstylenotetitle, ..., \sphinxstylewarningtitle, etc... which are used by
-%   default in the corresponding sphinx<notice> environments to replace at 6.2.0
-%   formerly hard-coded \sphinxstrong{#1}<space>
-%   Their definitions are in sphinxlatexstyletext.sty.
-
 
 % Provides: (also in sphinxlatexliterals.sty)
+% Only needed here by legacy (deprecated) sphinxlightbox environment.
 \providecommand*\sphinxvspacefixafterfrenchlists{%
    \ifvmode\ifdim\lastskip<\z@ \vskip\parskip\fi\else\par\fi
 }
 
-% Some are quite plain
-\newenvironment{sphinxseealso}[1]{\sphinxstyleseealsotitle{#1}}{}
-
 % This \dimen register is a legacy relic from Sphinx 1.5 which is used now
 % only for sphinxlightbox.  It is set in the sphinxadmonition environment.
 \newdimen\spx@notice@border
-
+% sphinxlightbox is now also a legacy relic, not used by Sphinx anymore
 \newenvironment{sphinxlightbox}{%
   \par
   \noindent{\color{spx@notice@bordercolor}%
@@ -65,58 +72,42 @@
              {\linewidth}{\spx@notice@border}}\hss}\allowbreak
   }% end of sphinxlightbox environment definition
 
-% note/hint/important/tip notices
+% Since 1.5 these environments are named individually sphinxnote, sphinxhint,
+% etc... to allow user to redefine them entirely.
 %
-% Since 1.5 these environments are named individually to allow user to
-% redefine them entirely.
-%
-% The Sphinx definitions were done like this, prior to 6.2.0:
+% The Sphinx definitions for note/hint/important/tip notices were done like
+% this, prior to 6.2.0:
 %
 % \newenvironment{sphinxhint}[1]
 %   {\begin{sphinxlightbox}\sphinxstrong{#1} }{\end{sphinxlightbox}}
 %
-% The more complex definition below will branch to sphinxheavybox if a certain
-% boolean associated to the notice type is true.  This boolean is set to true
-% whenever a CSS-named alike options for the notice type has been used in
-% sphinxsetup.  The old coding as above would still work, with the new options
-% being then simply ignored.  A user redefinition will probably either use
-% directly sphinxlightbox or sphinxheavybox or something else, with no need to
-% test the boolean.
-%
-% 6.2.0 also adds one layer of mark-up via \sphinxnotetitle etc..., because
-% the former \sphinxstrong{#1}<space> used a too generic \sphinxstrong.  But
-% perhaps the #1 should be passed over to sphinx{light,heavy}box as parameter.
-% Unfortunately replacing these environments with one-parameter environments
-% would be potentially a breaking change.  Anyway, sphinxpackageboxes.sty does not
-% provide a "titled" box; the caption of code-blocks is handled by extra
-% code in sphinxVerbatim.
-\newenvironment{sphinxnote}[1]
-  {\edef\spx@env{sphinx\ifspx@opt@heavynote heavy\else light\fi box}%
-   \expandafter\begin\expandafter{\spx@env}\sphinxstylenotetitle{#1}}
-  {\expandafter\end\expandafter{\spx@env}}
-\newenvironment{sphinxhint}[1]
-  {\edef\spx@env{sphinx\ifspx@opt@heavyhint heavy\else light\fi box}%
-   \expandafter\begin\expandafter{\spx@env}\sphinxstylehinttitle{#1}}
-  {\expandafter\end\expandafter{\spx@env}}
-\newenvironment{sphinximportant}[1]
-  {\edef\spx@env{sphinx\ifspx@opt@heavyimportant heavy\else light\fi box}%
-   \expandafter\begin\expandafter{\spx@env}\sphinxstyleimportanttitle{#1}}
-  {\expandafter\end\expandafter{\spx@env}}
-\newenvironment{sphinxtip}[1]
-  {\edef\spx@env{sphinx\ifspx@opt@heavytip heavy\else light\fi box}%
-   \expandafter\begin\expandafter{\spx@env}\sphinxstyletiptitle{#1}}
-  {\expandafter\end\expandafter{\spx@env}}
-
-% warning/caution/attention/danger/error  get more distinction
+% Then from 6.2.0 to 7.4.0 (exclusive) a more complex definition decided
+% to use either sphinxlightbox or sphinxheavybox according to whether
+% some CSS-like options had been used, for example for a background color.
+%
+% 6.2.0 also added one layer of mark-up via \sphinxnotetitle etc..., because
+% the former \sphinxstrong{#1}<space> used a too generic \sphinxstrong.
+%
+% At 7.4.0, sphinxheavybox environment is default for all types of notices
+% and also for seealso directive.
 %
+% The 7.4.0 sphinxheavybox has an "optional" argument [<type>], which actually
+% is mandatory and must be the admonition type.  It is needed only for the
+% the boolean \ifspx@<type>@border@open.
+% The 7.4.0 version of sphinxheavybox is executed *after* the suitable
+% \spx@boxes@fcolorbox@setup{<type>}.  Formerly it did it itself.
+%
+% Catch a missing mandatory [<type>] 
+\def\ifspx@@border@open{\PackageError{sphinxlatexadmonitions}
+                                     {Missing type for sphinxheavybox}
+                                     {Please check sphinxlatexadmonitions.sty
+                                       for comments}%
+                        \iffalse}
+
 % Code adapted from framed.sty's "snugshade" environment.
 % Nesting works (inner frames do not allow page breaks).
-\newenvironment{sphinxheavybox}{\par
-   % 6.2.0 allows to not have to distinguish here between warning type notices
-   % which always use sphinxheavybox or note type notices which might use it.
-   % (MEMO: it is not a problem here if there is no sphinx<type>ShadowColor,
-   %  as it used only if set)
-   \spx@boxes@fcolorbox@setup{\spx@noticetype}%
+\newenvironment{sphinxheavybox}[1][]{%
+   \par
    % Those are used by sphinxVerbatim if the \ifspx@inframed boolean is true
    \setlength{\FrameRule}{0.5\dimexpr\spx@boxes@border@top+\spx@boxes@border@bottom\relax}%
    % MEMO: prior to 5.1.0 \FrameSep was determined as 0.6\baselineskip -
@@ -148,7 +139,7 @@
    }%
    % 6.2.0 adds support for div.<notice type>_box-decoration-break=slice.
    % (it is yet undecided if slice style should inhibit a bottom shadow)
-   \csname ifspx@\spx@noticetype @border@open\endcsname
+   \csname ifspx@#1@border@open\endcsname
      \def\FirstFrameCommand
                {\spx@boxes@fcolorbox@setup@openbottom\FrameCommand}%
      \def\MidFrameCommand
@@ -205,16 +196,77 @@
 % Example:
 % \renewcommand{\sphinxwarningtitle}[1]{\textbf{#1}\par\smallskip
 %   {\color{sphinxwarningBorderColor}\hrule height1pt}\smallskip}
+%
+% - Since 7.4.0, all types of notices use sphinxheavybox and the default
+% for \sphinxstyle<type>title is mapped to using \sphinxdotitlerowwithicon{<type>}
+%
+% MEMO: except for the generic admonition directive (which uses "note" type)
+% the argument #1 in these environments has a postfixed colon originating
+% in Sphinx LaTeX writer legacy code.  The
+% \sphinxremovefinalcolon utility in sphinxlatexstyletext.sty can be used as
+% \sphinxremovefinalcolon{#1} from inside the definitions of
+% \sphinxstylenotetitle et al. commands.
+
+% Important: even prior to 5.1.0 it was not really possible to use directly
+% sphinxheavybox if not triggered from sphinxadmonition, because some
+% parameters were defined in sphinxadmonition.  This meant that the
+% sphinxwarning, sphinxcaution etc... environments (defined below) could not
+% be used directly in a document, they had to be triggered via
+% sphinxadmonition.  The sole data since 5.1.0 needed by sphinxheavybox is the
+% type of the notice which sphinxadmonition stores into \spx@noticetype.
+% Rather than rely on such a macro being set we have refactored sphinxheavybox
+% to take an optional argument (the various [note], [hint] etc...) to transmit
+% the notice type (it does not have to be an admonition type, only to be
+% something which \spx@boxes@fcolorbox@setup will be able to handle).
+% 
+% This way the environments sphinxwarning et al. as defined next can be used
+% directly in other contexts without originating from sphinxadmonition.  And
+% now we can let sphinxseealso use sphinxheavybox, despite the seealso
+% directive not being handled by Sphinx LaTeX writer as an admonition type.
+%
+% MEMO: the \spx@boxes@fcolorbox@setup{<type>} are executed first so that
+% \sphinxdotitlerowwithicon (see below) can inherit the box parameters, in
+% particular whether the top corners are rounded and fit exactly in the frame.
+%
+% MEMO: direct usage of these environment does not execute the div.<type>_TeXextras
+% and div.<type>_TexColor code, there are only done from the sphinxadmonition wrapper.
+\newenvironment{sphinxnote}[1]
+  {\spx@boxes@fcolorbox@setup{note}\begin{sphinxheavybox}[note]\sphinxstylenotetitle{#1}}
+  {\end{sphinxheavybox}}
+\newenvironment{sphinxhint}[1]
+  {\spx@boxes@fcolorbox@setup{hint}\begin{sphinxheavybox}[hint]\sphinxstylehinttitle{#1}}
+  {\end{sphinxheavybox}}
+\newenvironment{sphinxtip}[1]
+  {\spx@boxes@fcolorbox@setup{tip}\begin{sphinxheavybox}[tip]\sphinxstyletiptitle{#1}}
+  {\end{sphinxheavybox}}
+\newenvironment{sphinximportant}[1]
+  {\spx@boxes@fcolorbox@setup{important}\begin{sphinxheavybox}[important]\sphinxstyleimportanttitle{#1}}
+  {\end{sphinxheavybox}}
 \newenvironment{sphinxwarning}[1]
-  {\begin{sphinxheavybox}\sphinxstylewarningtitle{#1}}{\end{sphinxheavybox}}
+  {\spx@boxes@fcolorbox@setup{warning}\begin{sphinxheavybox}[warning]\sphinxstylewarningtitle{#1}}
+  {\end{sphinxheavybox}}
 \newenvironment{sphinxcaution}[1]
-  {\begin{sphinxheavybox}\sphinxstylecautiontitle{#1}}{\end{sphinxheavybox}}
+  {\spx@boxes@fcolorbox@setup{caution}\begin{sphinxheavybox}[caution]\sphinxstylecautiontitle{#1}}
+  {\end{sphinxheavybox}}
 \newenvironment{sphinxattention}[1]
-  {\begin{sphinxheavybox}\sphinxstyleattentiontitle{#1}}{\end{sphinxheavybox}}
+  {\spx@boxes@fcolorbox@setup{attention}\begin{sphinxheavybox}[attention]\sphinxstyleattentiontitle{#1}}
+  {\end{sphinxheavybox}}
 \newenvironment{sphinxdanger}[1]
-  {\begin{sphinxheavybox}\sphinxstyledangertitle{#1}}{\end{sphinxheavybox}}
+  {\spx@boxes@fcolorbox@setup{danger}\begin{sphinxheavybox}[danger]\sphinxstyledangertitle{#1}}
+  {\end{sphinxheavybox}}
 \newenvironment{sphinxerror}[1]
-  {\begin{sphinxheavybox}\sphinxstyleerrortitle{#1}}{\end{sphinxheavybox}}
+  {\spx@boxes@fcolorbox@setup{error}\begin{sphinxheavybox}[error]\sphinxstyleerrortitle{#1}}
+  {\end{sphinxheavybox}}
+% The "see also" was quite plain until 7.4.0 as it simply did
+% \newenvironment{sphinxseealso}[1]{\sphinxstyleseealsotitle{#1}}{}
+% Here we need to manually insert execution of div.seealso_TeX{color,extras} values
+\newenvironment{sphinxseealso}[1]
+  {\spx@boxes@fcolorbox@setup{seealso}%
+   \begin{sphinxheavybox}[seealso]\sphinxstyleseealsotitle{#1}%
+   \ifspx@seealso@withtextcolor\color{sphinxseealsoTextColor}\fi
+   \spx@seealso@TeXextras
+  }
+  {\end{sphinxheavybox}}
 
 % the main dispatch for all types of notices
 \newenvironment{sphinxadmonition}[2]{% #1=type, #2=heading
@@ -227,16 +279,93 @@
   % the more bulky "sphinx\spx@noticetype BgColor".
   \sphinxcolorlet{spx@notice@bordercolor}{sphinx#1BorderColor}%
   \sphinxcolorlet{spx@notice@bgcolor}{sphinx#1BgColor}%
-  \spx@notice@border \dimexpr\csname spx@#1@border\endcsname\relax
+  % At 7.4.0 there are no \spx@<type>@boder macros anymore only top, left,
+  % bottom, right.  For this legacy \spx@notice@border only needed by
+  % sphinxlightbox (which is not used by own Sphinx environments anymore)
+  % we thus use here @top
+  \spx@notice@border \dimexpr\csname spx@#1@border@top\endcsname\relax
   % trigger the sphinx<type> environment, #2=heading is passed as argument
   \begin{sphinx#1}{#2}%
+  % MEMO: the heading #2 will be typeset before the next lines are executed
   % 6.2.0 support of div.<type>_TeX{color,extras} options
   \csname ifspx@\spx@noticetype @withtextcolor\endcsname
          \color{sphinx\spx@noticetype TextColor}%
   \fi
+  % Other code to be executed at start of contents (after title)
   \csname spx@\spx@noticetype @TeXextras\endcsname
   }
-  % workaround some LaTeX "feature" of \end command (can't use "sphinx#1" here)
+  % workaround some LaTeX "feature" of \end command (i.e. can't use "sphinx#1" here)
   {\edef\spx@temp{\noexpand\end{sphinx\spx@noticetype}}\spx@temp}
 
+\newcommand\sphinxtitlerowtoppadding{5pt}
+\newcommand\sphinxtitlerowbottompadding{3pt}
+\newcommand\sphinxtitlerowaftericonspacecmd{\hskip0.75em\relax}
+\newcommand\sphinxdotitlerowwithicon[2]{% #1=type, #2=heading (without final colon)
+    \kern-\spx@boxes@padding@top
+    \noindent
+    \kern-\spx@boxes@padding@left % must have been configured by a prior \spx@boxes@fcolorbox@setup{<type>}
+    \begingroup
+     % inherit settings from the enclosing box and modify what is needed
+     \spx@boxes@border@top    =\z@
+     \spx@boxes@border@right  =\z@
+     \spx@boxes@border@bottom =\z@
+     \spx@boxes@border@left   =\z@
+     \spx@boxes@radius@bottomright@x=\z@
+     \spx@boxes@radius@bottomright@y=\z@
+     \spx@boxes@radius@bottomleft@x=\z@
+     \spx@boxes@radius@bottomleft@x=\z@
+     \spx@boxes@padding@top   =\sphinxtitlerowtoppadding\relax
+     \spx@boxes@padding@bottom=\sphinxtitlerowbottompadding\relax
+     \spx@boxes@withshadowfalse
+     \sphinxcolorlet{spx@boxes@backgroundcolor}{sphinx#1TtlBgColor}%
+     \spx@boxes@fcolorbox{%
+        \makebox[\linewidth][l]{%
+         \textcolor{sphinx#1TtlFgColor}{\@nameuse{sphinx#1TtlIcon}}%
+         \sphinxtitlerowaftericonspacecmd
+         \sphinxstrong{#2}%
+         \strut}%
+      }%
+    \endgroup
+    \kern-\spx@boxes@padding@right
+    \par\vskip-\parskip\kern\spx@boxes@padding@top
+}
+
+% #1 holds the localized name of the notice, postfixed with a colon.
+% \sphinxremovefinalcolon{#1} will typeset #1 without the colon.
+% Legacy definitions (done in sphinxlatexstyletext.sty) were all using
+% a boring plain \sphinxstrong{#1}, now we use a coloured title row.
+\newcommand\sphinxstylenotetitle     [1]{\sphinxdotitlerowwithicon{note}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstylehinttitle     [1]{\sphinxdotitlerowwithicon{hint}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstyleimportanttitle[1]{\sphinxdotitlerowwithicon{important}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstyletiptitle      [1]{\sphinxdotitlerowwithicon{tip}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstylewarningtitle  [1]{\sphinxdotitlerowwithicon{warning}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstylecautiontitle  [1]{\sphinxdotitlerowwithicon{caution}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstyleattentiontitle[1]{\sphinxdotitlerowwithicon{attention}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstyledangertitle   [1]{\sphinxdotitlerowwithicon{danger}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstyleerrortitle    [1]{\sphinxdotitlerowwithicon{error}{\sphinxremovefinalcolon{#1}}}
+\newcommand\sphinxstyleseealsotitle  [1]{\sphinxdotitlerowwithicon{seealso}{\sphinxremovefinalcolon{#1}}}
+%
+% A utility to remove a final colon.  Removing last token is not easy in
+% LaTeX, and there are additional complications:
+% - some languages will make the : "active" in document body,
+% - the generic admonition ends up using "note", so for \sphinxnotetitle to
+%   use it safely, the utility has to allow an input not having any final colon.
+% - a bit far-fetched but maybe there is more than one colon inside the input
+%   (possible from a generic admonition title).
+% Hence the scary code.
+\newcommand\sphinxremovefinalcolon[1]{% #1 is the "active" : TeX token
+% Prior to 7.4.0 this was defined with \protected\def but we do not
+% see what usefulness this could have.
+\renewcommand\sphinxremovefinalcolon[1]{%
+   % complications due to : possibly "active"
+   \begingroup\ifnum\catcode`:=\active
+                    \def\x####1#1\relax{####1}%
+               \else\def\x####1:\relax{####1}\fi
+   \expandafter\endgroup\x##1\relax
+   % trick to let \x work also if input ##1 has no ending colon
+   \@gobblefour#1\relax:\relax\relax\relax
+   }%
+}% end of wrapper to inject active :
+\begingroup\catcode`:\active\expandafter\endgroup\sphinxremovefinalcolon:
+
 \endinput
diff --git a/sphinx/texinputs/sphinxlatexliterals.sty b/sphinx/texinputs/sphinxlatexliterals.sty
index 3a73a76619e..8acea9f7638 100644
--- a/sphinx/texinputs/sphinxlatexliterals.sty
+++ b/sphinx/texinputs/sphinxlatexliterals.sty
@@ -1,7 +1,7 @@
 %% LITERAL BLOCKS
 %
 % change this info string if making any custom modification
-\ProvidesFile{sphinxlatexliterals.sty}[2023/04/01 code-blocks and parsed literals]
+\ProvidesFile{sphinxlatexliterals.sty}[2024/07/01 v7.4.0 code-blocks and parsed literals]
 
 % Provides support for this output mark-up from Sphinx latex writer:
 %
@@ -34,6 +34,7 @@
 % - needspace
 % - sphinxpackageboxes
 \RequirePackage{sphinxpackageboxes}
+% 7.4.0 removes unneeded usage of \spx@boxes@border
 
 % also in sphinxlatexadmonitions.sty:
 % This is a workaround to a "feature" of French lists, when literal block
@@ -224,7 +225,6 @@
        \spx@boxes@border@right\z@
        \spx@boxes@border@bottom\z@
        \spx@boxes@border@left\z@
-       \spx@boxes@border\z@
        % MEMO: rounded corners still make sense in presence of a background
        % color, so we do not force the fcolorbox@rectangle here
     \fi
@@ -670,25 +670,18 @@
        \def\sphinxVerbatim@Before
            {\sphinxVerbatim@Title\nointerlineskip
             \kern\dimexpr-\dp\strutbox+\sphinxbelowcaptionspace
-                 % if no frame (code-blocks inside table cells), remove
-                 % the top padding (better visually)
-                 \ifspx@opt@verbatimwithframe\else
-                    % but we must now check if there is a background color
-                    % MEMO: "fcolorbox@setup" will have been done by time of use
-                    \ifspx@boxes@withbackgroundcolor\else-\spx@boxes@padding@top\fi
-                \fi
+                 % MEMO: prior to 7.4.0 a test was done for presence or
+                 % not of a frame and if not top padding was removed if
+                 % no background color.  A background color is now always
+                 % assumed, so this got removed.
                  % caption package adds \abovecaptionskip vspace, remove it
-                 \spx@ifcaptionpackage{-\abovecaptionskip}{}\relax}%
+            \spx@ifcaptionpackage{-\abovecaptionskip}{}\relax}%
      \else
        \vskip\sphinxverbatimsmallskipamount
        \def\sphinxVerbatim@After
           {\nointerlineskip\kern\dimexpr\dp\strutbox
-            \ifspx@opt@verbatimwithframe\else
-                    % but we must now check if there is a background color
-                    % MEMO: "fcolorbox@setup" will have been done by time of use
-                    \ifspx@boxes@withbackgroundcolor\else-\spx@boxes@padding@bottom\fi
-            \fi
-            \spx@ifcaptionpackage{-\abovecaptionskip}{}\relax
+           % MEMO: 7.4.0 removes here too an optional removal of bottom padding
+           \spx@ifcaptionpackage{-\abovecaptionskip}{}\relax
            \sphinxVerbatim@Title}%
      \fi
      \def\@captype{literalblock}%
diff --git a/sphinx/texinputs/sphinxlatexstyletext.sty b/sphinx/texinputs/sphinxlatexstyletext.sty
index d90009035d2..fe7ec33bf2e 100644
--- a/sphinx/texinputs/sphinxlatexstyletext.sty
+++ b/sphinx/texinputs/sphinxlatexstyletext.sty
@@ -1,45 +1,11 @@
 %% TEXT STYLING
 %
 % change this info string if making any custom modification
-\ProvidesFile{sphinxlatexstyletext.sty}[2023/07/23 text styling]
+\ProvidesFile{sphinxlatexstyletext.sty}[2024/07/01 v7.4.0 text styling]
 
-% Basically everything here consists of macros which are part of the latex
-% markup produced by the Sphinx latex writer
-
-% But those arise rather from the default definitions of the respective
-% latex environments done in sphinxlatexadmonitions.sty
-\def\sphinxstylenotetitle   #1{\sphinxstrong{#1} }
-\let\sphinxstylehinttitle     \sphinxstylenotetitle % #1 holds the localized notice name
-\let\sphinxstyleimportanttitle\sphinxstylenotetitle % followed by a colon
-\let\sphinxstyletiptitle      \sphinxstylenotetitle
-\let\sphinxstylewarningtitle  \sphinxstylenotetitle
-\let\sphinxstylecautiontitle  \sphinxstylenotetitle
-\let\sphinxstyleattentiontitle\sphinxstylenotetitle
-\let\sphinxstyledangertitle   \sphinxstylenotetitle
-\let\sphinxstyleerrortitle    \sphinxstylenotetitle
-\def\sphinxstyleseealsotitle#1{\sphinxstrong{#1}\par\nopagebreak}
-%
-% A utility to remove a final colon.  Removing last token is not easy in
-% LaTeX, and there are additional complications:
-% - some languages will make the : "active" in document body,
-% - the generic admonition ends up using "note", so for \sphinxnotetitle to
-%   use it safely, the utility has to allow an input not having any final colon.
-% - a bit far-fetched but maybe there is more than one colon inside the input
-%   (possible from a generic admonition title).
-% Hence the scary code.
-\def\sphinxremovefinalcolon#1{% #1 is the "active" : TeX token
-\protected\def\sphinxremovefinalcolon ##1{%
-   % complications due to : possibly "active"
-   \begingroup\ifnum\catcode`:=\active
-                    \def\x####1#1\relax{####1}%
-               \else\def\x####1:\relax{####1}\fi
-   \expandafter\endgroup\x##1\relax
-   % trick to let \x work also if input ##1 has no ending colon
-   \@gobblefour#1\relax:\relax\relax\relax
-   }%
-}% end of wrapper to inject active :
-\begingroup\catcode`:\active\expandafter\endgroup\sphinxremovefinalcolon:
-% See doc/latex.rst for an example.
+% 7.4.0 has moved all that is related to admonitions to sphinxlatexadmonitions.sty
+% Most verything left here consists of macros which are part of the latex markup
+% produced by the Sphinx LaTeX writer.
 
 % Some custom font markup commands.
 \protected\def\sphinxstrong#1{\textbf{#1}}
diff --git a/sphinx/texinputs/sphinxlatextables.sty b/sphinx/texinputs/sphinxlatextables.sty
index 380fc1705e4..9f3944a6591 100644
--- a/sphinx/texinputs/sphinxlatextables.sty
+++ b/sphinx/texinputs/sphinxlatextables.sty
@@ -1,7 +1,7 @@
 %% TABLES (WITH SUPPORT FOR MERGED CELLS OF GENERAL CONTENTS)
 %
 % change this info string if making any custom modification
-\ProvidesFile{sphinxlatextables.sty}[2022/08/15 tables]%
+\ProvidesFile{sphinxlatextables.sty}[2024/07/01 v7.4.0 tables]%
 
 % Provides support for this output mark-up from Sphinx latex writer
 % and table templates:
@@ -42,6 +42,11 @@
 % - \sphinxthistablewithnocolorrowsstyle
 % - \sphinxthistablewithvlinesstyle
 % - \sphinxthistablewithnovlinesstyle
+% 
+% Also provides user command (see docs)
+% - \sphixncolorblend
+%   (Sphinx 7.4.0 now requires xcolor, so \sphinxcolorblend does not check
+%    its availability anymore) 
 %
 % Executes \RequirePackage for:
 %
@@ -513,19 +518,6 @@
     \fi
 }
 \def\sphinxcolorblend#1{\gdef\spx@colorblendparam{{#1}}\spx@table@hackCT@colorblend}
-% Either xcolor.sty exists on user system and has been loaded by sphinx.sty,
-% or it does not exist, so we can use \@ifpackageloaded without delaying.
-\@ifpackageloaded{xcolor}%
-  {}%
-  {\def\sphinxcolorblend#1{%
-\PackageWarning{sphinx}{This table uses \string\sphinxcolorblend\space
-  but xcolor is not in\MessageBreak
-  the TeX/LaTeX installation, the command will be\MessageBreak
-  ignored in this and the next tables}%
-   \global\let\sphinxcolorblend\@gobble
-   \sphinxbuildwarning{colorblend}%
-   }%
-  }
 
 
 %%%%%%%%%%%%%%%%%%
diff --git a/sphinx/texinputs/sphinxpackageboxes.sty b/sphinx/texinputs/sphinxpackageboxes.sty
index b0d3707062f..6784225ea63 100644
--- a/sphinx/texinputs/sphinxpackageboxes.sty
+++ b/sphinx/texinputs/sphinxpackageboxes.sty
@@ -1,7 +1,12 @@
 %% COLOURED BOXES
 %
 % change this info string if making any custom modification
-\ProvidesPackage{sphinxpackageboxes}[2023/03/19 v6.2.0 advanced colored boxes]
+\ProvidesPackage{sphinxpackageboxes}[2024/07/01 v7.4.0 advanced colored boxes]
+% 7.4.0 removes usage of some booleans "...withbackgroundcolor" and
+% "...withbordercolor" as well as \spx@boxes@border dimen which was
+% actually really needed nowhere.  This was done in sync with changes in
+% sphinx.sty, sphinxlatexadmonitions.sty and sphinxlatexliterals.sty.
+%
 % Optionally executes \RequirePackage for:
 %
 % - pict2e.  Ideally we would like to use the v0.4a 2020/08/16 release of this
@@ -78,15 +83,13 @@
 %%%%%%%%%%%%%%%%
 % Internal registers, conditionals, colors to be configured by each caller
 % via a preliminary "setup" call
-%
 \newif\ifspx@boxes@withshadow
 \newif\ifspx@boxes@insetshadow
-\newif\ifspx@boxes@withbackgroundcolor
+%%% \newif\ifspx@boxes@withbackgroundcolor % removed at 7.4.0
 \newif\ifspx@boxes@withshadowcolor
-\newif\ifspx@boxes@withbordercolor
+%%% \newif\ifspx@boxes@withbordercolor     % removed at 7.4.0
 \newif\ifspx@boxes@shadowinbbox
 %
-\newdimen\spx@boxes@border
 \newdimen\spx@boxes@border@top
 \newdimen\spx@boxes@border@right
 \newdimen\spx@boxes@border@bottom
@@ -150,7 +153,6 @@
   \spx@boxes@border@right \dimexpr\@nameuse{spx@#1@border@right}\relax
   \spx@boxes@border@bottom\dimexpr\@nameuse{spx@#1@border@bottom}\relax
   \spx@boxes@border@left  \dimexpr\@nameuse{spx@#1@border@left}\relax
-  \spx@boxes@border       \dimexpr\@nameuse{spx@#1@border}\relax
   %
   \spx@boxes@padding@top   \dimexpr\@nameuse{spx@#1@padding@top}\relax
   \spx@boxes@padding@right \dimexpr\@nameuse{spx@#1@padding@right}\relax
@@ -200,19 +202,9 @@
      \spx@boxes@insetshadowfalse
   \fi
   %
-  \@nameuse{ifspx@#1@withbordercolor}%
-    \spx@boxes@withbordercolortrue
     \sphinxcolorlet{spx@boxes@bordercolor}{sphinx#1BorderColor}%
-  \else
-    \spx@boxes@withbordercolorfalse
-  \fi
   %
-  \@nameuse{ifspx@#1@withbackgroundcolor}%
-    \spx@boxes@withbackgroundcolortrue
     \sphinxcolorlet{spx@boxes@backgroundcolor}{sphinx#1BgColor}%
-  \else
-    \spx@boxes@withbackgroundcolorfalse
-  \fi
   %
   \@nameuse{ifspx@#1@withshadowcolor}%
     \spx@boxes@withshadowcolortrue
@@ -447,14 +439,12 @@
   \fi
   % BACKGROUND
   % draw background and move back to reference point
-  \ifspx@boxes@withbackgroundcolor
    {\color{spx@boxes@backgroundcolor}%
     \vrule\@height\ht\spx@tempboxa
           \@depth\dp\spx@tempboxa
           \@width\wd\spx@tempboxa
     \kern-\wd\spx@tempboxa
     }%
-  \fi
   % BOX SHADOW
   % draw shadow and move back to reference point
   \ifspx@boxes@withshadow
@@ -494,13 +484,8 @@
        }% end of \vbox
   \fi % end of shadow drawing, and we are back to horizontal reference point
   % BOX BORDER
-  \vbox{\ifspx@boxes@withbordercolor
-            \color{spx@boxes@bordercolor}%
-        \else
-            % 6.2.0: guard against a \color command in contents whose effect
-            % could leak to border at a pagebreak
-            \normalcolor
-        \fi
+  % 7.4.0 requires a set border color
+  \vbox{\color{spx@boxes@bordercolor}%
         \hrule\@height\spx@boxes@border@top
            \kern-\spx@boxes@border@top
         \setbox\spx@tempboxb\hb@xt@\wd\spx@tempboxa
@@ -540,14 +525,13 @@
 \def\spx@boxes@fcolorbox@insetshadow{%
   % BACKGROUND
   % draw background and move back to reference point
-  \ifspx@boxes@withbackgroundcolor
+  % 6.4.0 always assumes a background color
    {\color{spx@boxes@backgroundcolor}%
     \vrule\@height\ht\spx@tempboxa
           \@depth\dp\spx@tempboxa
           \@width\wd\spx@tempboxa
     \kern-\wd\spx@tempboxa
     }%
-  \fi
   % BOX SHADOW
   % draw shadow and move back to reference point
   \ifspx@boxes@withshadow
@@ -589,13 +573,8 @@
          }% end of \hbox, attention its depth is only |yoffset| if yoffset<0
   \fi % end of inset shadow drawing, and we are back to horizontal reference point
   % BOX BORDER
-  \vbox{\ifspx@boxes@withbordercolor
-            \color{spx@boxes@bordercolor}%
-        \else
-            % 6.2.0: guard against a \color command in contents whose effect
-            % could leak to border at a pagebreak
-            \normalcolor
-        \fi
+  % 7.4.0 requires a set border color
+  \vbox{\color{spx@boxes@bordercolor}%
         \hrule\@height\spx@boxes@border@top
            \kern-\spx@boxes@border@top
         \setbox\spx@tempboxb\hb@xt@\wd\spx@tempboxa
@@ -807,17 +786,11 @@
       \fi
       \spx@boxes@border@defpath% must be redone after each \fillpath! (even if
                                % was in a  \put)
-      \ifspx@boxes@withbordercolor
+      % 7.4.0 requires a set border color
          \color{spx@boxes@bordercolor}%
-      \else
-         \normalcolor
-      \fi
       \fillpath
-      \ifspx@boxes@withbackgroundcolor
+      % and backgroundcolor command
          \color{spx@boxes@backgroundcolor}%
-      \else
-         \color{white}%
-      \fi
       \edef\spx@width{\number\dimexpr\spx@width-\spx@boxes@border@left
                                                -\spx@boxes@border@right sp}%
       \edef\spx@height{\number\dimexpr\spx@height-\spx@boxes@border@top