Fix CSS bleed in button component.

[jasmussen]

Alternative to #22263. This fixes a CSS bleed issue for the button component when used inside the editing canvas.

When an editor style is added, which restyles the button element, it bleeds into the button component. This addresses that.

Example CSS:

input,
button,
textarea {
	padding: 12px 18px;
	font-size: 18px;
}

#22263 took a slightly more dangerous approach that might cause issues, but this approach should be rather safe, as it's adding to an existing rule that fixes the same issue but for fonts.

Before:

After:

[github-actions]

Size Change: +10.5 kB (0%)

Total Size: 1.12 MB

Filename	Size	Change
build/block-directory/index.js	6.93 kB	+1 B
build/block-editor/index.js	105 kB	+9 B (0%)
build/block-editor/style-rtl.css	10.8 kB	+18 B (0%)
build/block-editor/style.css	10.8 kB	+18 B (0%)
build/block-library/editor-rtl.css	7.17 kB	-51 B (0%)
build/block-library/editor.css	7.17 kB	-51 B (0%)
build/block-library/index.js	119 kB	+226 B (0%)
build/block-library/style-rtl.css	7.48 kB	+1 B
build/block-library/style.css	7.48 kB	-1 B
build/blocks/index.js	48.1 kB	-2 B (0%)
build/components/index.js	190 kB	+7.45 kB (3%)
build/compose/index.js	9.24 kB	+2.57 kB (27%)	🚨
build/core-data/index.js	11.4 kB	+22 B (0%)
build/data/index.js	8.42 kB	-7 B (0%)
build/edit-post/index.js	302 kB	-34 B (0%)
build/edit-post/style-rtl.css	12.2 kB	+14 B (0%)
build/edit-post/style.css	12.2 kB	+13 B (0%)
build/edit-site/style-rtl.css	5.25 kB	+31 B (0%)
build/edit-site/style.css	5.25 kB	+31 B (0%)
build/editor/index.js	44.6 kB	+299 B (0%)
build/editor/style-rtl.css	5.06 kB	-16 B (0%)
build/editor/style.css	5.06 kB	-17 B (0%)
build/element/index.js	4.65 kB	-1 B
build/i18n/index.js	3.56 kB	+1 B
build/keyboard-shortcuts/index.js	2.51 kB	-2 B (0%)
build/nux/index.js	3.4 kB	-2 B (0%)
build/redux-routine/index.js	2.85 kB	-1 B
build/rich-text/index.js	14.8 kB	-2 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
build/a11y/index.js	1.02 kB	0 B
build/annotations/index.js	3.62 kB	0 B
build/api-fetch/index.js	3.39 kB	0 B
build/autop/index.js	2.83 kB	0 B
build/blob/index.js	620 B	0 B
build/block-directory/style-rtl.css	790 B	0 B
build/block-directory/style.css	791 B	0 B
build/block-library/theme-rtl.css	683 B	0 B
build/block-library/theme.css	685 B	0 B
build/block-serialization-default-parser/index.js	1.88 kB	0 B
build/block-serialization-spec-parser/index.js	3.1 kB	0 B
build/components/style-rtl.css	17.1 kB	0 B
build/components/style.css	17.1 kB	0 B
build/data-controls/index.js	1.29 kB	0 B
build/date/index.js	5.47 kB	0 B
build/deprecated/index.js	772 B	0 B
build/dom-ready/index.js	568 B	0 B
build/dom/index.js	3.11 kB	0 B
build/edit-navigation/index.js	6.6 kB	0 B
build/edit-navigation/style-rtl.css	857 B	0 B
build/edit-navigation/style.css	856 B	0 B
build/edit-site/index.js	12.8 kB	0 B
build/edit-widgets/index.js	7.73 kB	0 B
build/edit-widgets/style-rtl.css	4.59 kB	0 B
build/edit-widgets/style.css	4.59 kB	0 B
build/editor/editor-styles-rtl.css	425 B	0 B
build/editor/editor-styles.css	428 B	0 B
build/escape-html/index.js	733 B	0 B
build/format-library/index.js	7.64 kB	0 B
build/format-library/style-rtl.css	502 B	0 B
build/format-library/style.css	502 B	0 B
build/hooks/index.js	2.13 kB	0 B
build/html-entities/index.js	622 B	0 B
build/is-shallow-equal/index.js	711 B	0 B
build/keycodes/index.js	1.94 kB	0 B
build/list-reusable-blocks/index.js	3.13 kB	0 B
build/list-reusable-blocks/style-rtl.css	226 B	0 B
build/list-reusable-blocks/style.css	226 B	0 B
build/media-utils/index.js	5.29 kB	0 B
build/notices/index.js	1.79 kB	0 B
build/nux/style-rtl.css	616 B	0 B
build/nux/style.css	613 B	0 B
build/plugins/index.js	2.56 kB	0 B
build/primitives/index.js	1.5 kB	0 B
build/priority-queue/index.js	789 B	0 B
build/server-side-render/index.js	2.68 kB	0 B
build/shortcode/index.js	1.7 kB	0 B
build/token-list/index.js	1.28 kB	0 B
build/url/index.js	4.02 kB	0 B
build/viewport/index.js	1.84 kB	0 B
build/warning/index.js	1.14 kB	0 B
build/wordcount/index.js	1.17 kB	0 B

_{compressed-size-action}

[jasmussen]

It fixes these buttons also:

[youknowriad]

I'm fine with this fix but it only works on edit-post (not on edit-widgets, not on edit-site).

[jasmussen]

Is there a better place than visual editor to put this, you think?

[youknowriad]

I don't know, we could just duplicate the code in edit-site for now (as edit-widgets don't use editor styles) and comment on why it's needed.

[jasmussen]

I think I fixed it Riad: