🐛 fix(home): add !important + direct .md-typeset fallback to force text visibility

Previous attempts used :root / [data-md-color-scheme] selectors without
!important, but MkDocs Material's internal CSS variable resolution chain
(built into the 200KB+ main bundle) resolves --md-typeset-color after our
extra.css loads, overriding all previous values.

This fix adds:
1. !important on all --md-* color variables
2. Direct .md-typeset { color: #a0a0b8 !important } as element-level fallback
   bypassing the entire CSS variable resolution chain

Author: ouyangyipeng

docs/stylesheets/extra.css

@@ -38,13 +38,20 @@
 }
 
 /* ── Fix #5: CRITICAL — text must be visible on dark background ──── */
-/* MkDocs Material uses [data-md-color-scheme] selectors with higher
-   specificity than :root. Must match their selector chain. */
+/* MkDocs Material resolves --md-typeset-color from its internal chain
+   which overrides our :root settings. Use !important on the exact
+   selectors MkDocs uses, plus a direct .md-typeset color fallback. */
 [data-md-color-scheme="default"],
 [data-md-color-scheme="slate"] {
-  --md-typeset-color: #a0a0b8;
-  --md-typeset-a-color: #a78bfa;
-  --md-default-fg-color--light: #6b6b80;
+  --md-default-fg-color: #a0a0b8 !important;
+  --md-typeset-color: #a0a0b8 !important;
+  --md-typeset-a-color: #a78bfa !important;
+  --md-default-fg-color--light: #6b6b80 !important;
+}
+
+/* Direct element-level fallback — resolves variable resolution chain issues */
+.md-typeset {
+  color: #a0a0b8 !important;
 }
 
 /* ── Body Background ────────────────────────────────────────────── */