style(css): consolidate global selector rules and remove duplicates

- Merge three separate `*` selector blocks into one for better maintainability
- Remove duplicate "Glassmorphism Utilities" comment

src/index.css

@@ -70,7 +70,6 @@
   }
 }
 
-/* Glassmorphism Utilities */
 /* Glassmorphism Utilities */
 .glass {
   background: rgba(255, 255, 255, 0.7);
@@ -131,6 +130,8 @@
 /* 全局基础样式 */
 * {
   box-sizing: border-box;
+  scrollbar-width: none; /* Firefox */
+  -ms-overflow-style: none; /* IE 10+ */
 }
 
 html {
@@ -158,16 +159,6 @@ html.dark {
   display: none;
 }
 
-/* Firefox */
-* {
-  scrollbar-width: none;
-}
-
-/* IE 10+ */
-* {
-  -ms-overflow-style: none;
-}
-
 /* 焦点样式 */
 *:focus-visible {
   @apply outline-2 outline-blue-500 outline-offset-2;