feat: Start using native accent color for about pages, p=#10847, c=common, tabs

src/zen/common/styles/zen-theme.css

@@ -12,13 +12,12 @@
 :root {
   /* Default values */
   --zen-border-radius: 7px;
-  --zen-primary-color: #ffb787;
+  --zen-primary-color: AccentColor;
 
   --zen-background-opacity: 1;
 
   /* Branding */
   --zen-branding-dark: #1d1d1d;
-  --zen-branding-coral: #f76f53;
   --zen-branding-paper: #ebebeb;
 
   --zen-branding-bg: light-dark(var(--zen-branding-paper), var(--zen-branding-dark));

src/zen/tabs/zen-tabs.css

@@ -36,9 +36,7 @@
       * - Bookmarks toolbar is visible OR
       * - The container is explicitly marked to hide controls (e.g., on Linux with reversed controls)
       */
-    :root[zen-has-bookmarks] & {
-%include zen-tabs/vertical-tabs-topbar.inc.css
-    }
+    :root[zen-has-bookmarks] &,
     &[should-hide='true'] {
 %include zen-tabs/vertical-tabs-topbar.inc.css
     }

src/zen/tabs/zen-tabs/vertical-tabs-topbar.inc.css

@@ -3,6 +3,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
+
+--zen-toolbar-height: 34px;
+
 height: var(--zen-toolbar-height);
 z-index: 1;