fix(back-to-top): position (#1816)

.changeset/whole-pillows-run.md

@@ -0,0 +1,4 @@
+---
+"@rhds/elements": patch
+---
+`<rh-back-to-top>`: builds-in the style guidelines in: back to top is fixed and always on top. Note that this change removes previously undocumented CSS custom properties `--rh-back-to-top-position-right` and `--rh-back-to-top-position-bottom`.

elements/rh-back-to-top/rh-back-to-top.css

@@ -1,7 +1,8 @@
 :host {
-  position: absolute;
-  right: var(--rh-space-xl, 24px);
-  bottom: var(--rh-space-xl, 24px);
+  position: fixed;
+  z-index: 1000;
+  inset-inline-end: var(--rh-space-xl, 24px);
+  inset-block-end: var(--rh-space-xl, 24px);
 }
 
 [part="trigger"] {
@@ -54,7 +55,7 @@ span {
 
 @media (min-width: 768px) {
   :host {
-    right: var(--rh-back-to-top-position-right, var(--rh-space-3xl, 48px));
-    bottom: var(--rh-back-to-top-position-bottom, var(--rh-space-3xl, 48px));
+    inset-inline-end: var(--rh-space-3xl, 48px);
+    inset-block-end: var(--rh-space-3xl, 48px);
   }
 }

elements/rh-back-to-top/rh-back-to-top.ts

@@ -15,11 +15,8 @@ import styles from './rh-back-to-top.css';
  * to the top of a lengthy content page.
  *
  * @summary A shortcut to the top of the page content
- *
  * @csspart trigger - back to top link anchor element
-
  * @slot - Text for the back to top link
- *
  */
 @customElement('rh-back-to-top')
 export class RhBackToTop extends LitElement {