Adjust card width on desktop

The card width was too wide on desktop. Adjusted the width to be slightly smaller than the four icon area at the bottom.

src/index.css

@@ -169,6 +169,25 @@
       @apply rounded-xl overflow-hidden;
     }
   }
+  
+  /* 데스크탑 화면에서의 추가 스타일 */
+  @media (min-width: 769px) {
+    #root {
+      @apply px-4;
+    }
+    
+    .desktop-container {
+      @apply max-w-[500px] mx-auto;
+    }
+    
+    .desktop-card {
+      @apply max-w-[500px] mx-auto;
+    }
+    
+    .neuro-card {
+      @apply max-w-[500px] mx-auto;
+    }
+  }
 }
 
 .font-inter {