fix typo

Author: Fukusan64

_sass/pages/index.scss

@@ -74,7 +74,7 @@
   }
 
   @media (max-width: 768px) {
-    grid-template-columns: 1fr; /* 1x1表示 */
+    grid-template-columns: 1fr; /* 1x4表示 */
   }
 }