fix(navigation): stop the public reset from overriding the reference menu styles

The public bundle loads after main.min.css, and its bare-element rules
won on equal specificity:

- img { display: block; height: auto } replaced the inline image baseline
  the menu relies on (Bootstrap img{vertical-align:middle} + main.css
  img{max-height:100%}). Menu glyphs and graphic-card thumbnails were
  pulled out of the inline flow, breaking row height and baseline.
  Scoped the reset to content and restored the inline baseline inside
  .header / .mobile-header.
- html { overflow-x: clip/hidden } made the root a clipping context,
  which crops the position:fixed senior mega menu and its drop panels.
  The horizontal-overflow guard now lives on body only.

Rebuilt public.css / public.min.css.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

assets/css/frontend/base.css

@@ -2,14 +2,15 @@
  * Jio Main v5 — 博客/个人站完整前端
  */
 
-/* 防止 hero 等使用 100vw / full-bleed 时产生横向滚动条 */
-html,
+/* 防止 hero 等使用 100vw / full-bleed 时产生横向滚动条。
+ *
+ * 只在 body 上裁剪：html 一旦建立裁剪上下文，position: fixed 的
+ * 导航 mega menu（.sub-menu.senior-submenu）和下拉面板会被一并裁掉。 */
 body {
   overflow-x: clip;
 }
 
 @supports not (overflow-x: clip) {
-  html,
   body {
     overflow-x: hidden;
   }