Update index.html

index.html

@@ -508,13 +508,18 @@ body {
         .audio-only-mode.active {
           display: block;
         }
+ 
 .main-content {
-    width: 100%;
+    position: relative;
+    z-index: 10;
+      width: 100%;
     max-width: 1200px;
     padding: 20px;
-    box-sizing: border-box; /* paddingを幅に含める */
-}
-    </style>
+    color: white;
+    max-width: 1200px;
+    margin: 0 auto;
+box-sizing: border-box; 
+}  </style>
 <style>
     html, body {
         margin: 0;