增加移动端注册按钮高度以填充导航栏

- 767px 断点: navbar 50px -> 按钮 46px
- 575px 断点: navbar 48px -> 按钮 44px
- 360px 断点: navbar 44px -> 按钮 40px

现在注册按钮能占据导航栏的大部分高度，看起来更加平衡

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

css/index.css

@@ -2550,7 +2550,7 @@ html {
     padding: 0 10px !important;
     font-size: 10px !important;
     min-width: auto !important;
-    height: 32px !important;
+    height: 46px !important;
     line-height: 1 !important;
     display: flex !important;
     align-items: center !important;
@@ -3107,7 +3107,7 @@ html {
     padding: 0 10px !important;
     font-size: 10px !important;
     min-width: auto !important;
-    height: 32px !important;
+    height: 44px !important;
     line-height: 1 !important;
     display: flex !important;
     align-items: center !important;
@@ -3609,7 +3609,7 @@ html {
     padding: 0 8px !important;
     font-size: 9px !important;
     min-width: auto !important;
-    height: 28px !important;
+    height: 40px !important;
     line-height: 1 !important;
     display: flex !important;
     align-items: center !important;