fix(a11y): fix contrast of keyboard shortcut labels

kbd elements inherit the red code text color (#e74c3c), which gives
~3.82:1 against white — below the 4.5:1 required for normal text
(WCAG 1.4.3 / BITV 9.1.4.3). The light border (#a6a6a6) also falls
short of the 3:1 required for UI component boundaries (WCAG 1.4.11).

Override text color to #c0392b (~5.4:1) and border to #767676 (~4.5:1).

Fixes #9675

Signed-off-by: John Molakvoæ (skjnldsv) <skjnldsv@protonmail.com>

Author: skjnldsv

_shared_assets/static/custom.css

@@ -65,6 +65,16 @@ h6 {
 	background: rgba(0, 130, 201, 0.1)
 }
 
+/* kbd elements pick up the red code text color (#e74c3c) which gives
+   ~3.82:1 on white — below the 4.5:1 required by WCAG AA / BITV 9.1.4.3.
+   Override to a darker red (~5.4:1) and darken the border so the
+   key outline meets the 3:1 non-text contrast requirement. */
+.rst-content kbd,
+kbd {
+	color: #c0392b;
+	border-color: #767676;
+}
+
 /* Fix code within tables - remove too big margins */
 .rst-content td {
 	div[class^="highlight"]:last-of-type,