feat: 优化移动端学习与证书体验

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

index.html

@@ -9,8 +9,9 @@
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-      content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0"
+      content="width=device-width, initial-scale=1.0, user-scalable=no, viewport-fit=cover"
     />
+
     <meta
       name="referrer"
       content="no-referrer"