fix: widen doc content area and narrow TOC to prevent sidebar overlap (#109)

- Increase content column from 75% to 80% of container width
- Reduce TOC column from 25% to 20% to push it further right
- Add overflow-x: auto to content area to prevent wide tables/code
  from bleeding into the TOC column
- Add left border + padding on TOC for visual separation

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: JusterZhu

website/src/css/custom.css

@@ -602,6 +602,31 @@
    TOC  (right sidebar)
    ════════════════════════════════════════════════════════════════ */
 
+/* ── Push TOC further right, give main content more room ── */
+@media (min-width: 997px) {
+  /* Widen content column from 75% → 80% */
+  [class*="docMainContainer"] [class*="docItemCol"] {
+    max-width: 80% !important;
+  }
+
+  /* Narrow TOC column from 25% → 20% */
+  [class*="docMainContainer"] .col--3 {
+    --ifm-col-width: calc(20%);
+  }
+
+  /* Prevent wide content (tables, code) from bleeding into TOC */
+  [class*="docItemCol"] .markdown {
+    overflow-x: auto;
+  }
+
+  /* Visual separation between content and TOC */
+  .table-of-contents {
+    padding-left: 1rem;
+    margin-left: 0.25rem;
+    border-left: 1px solid var(--ifm-color-emphasis-200);
+  }
+}
+
 .table-of-contents__link {
   font-size: 0.85rem;
   transition: color 0.15s;