revert legacy comment and fine tune legacy aspect ratio

Author: wxiaoguang

web_src/css/features/heatmap.css

@@ -18,11 +18,14 @@
 
 /* Fallback height adjustment above for browsers that don't support container queries */
 @supports not (container-type: inline-size) {
+  /* before the Vue component is mounted, show a loading indicator with dummy size */
+  /* the ratio is guesswork, see https://github.com/razorness/vue3-calendar-heatmap/issues/26 */
+
   #user-heatmap.is-loading {
-    aspect-ratio: 5.415;
+    aspect-ratio: 5.4823972051; /* the size is about 816 x 148.84 */
   }
   .user.profile #user-heatmap.is-loading {
-    aspect-ratio: 5.645;
+    aspect-ratio: 5.6290608387; /* the size is about 953 x 169.3 */
   }
 }