Fix mobile pub thumbnail to maintain square aspect ratio

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: zlyfunction

index.html

@@ -608,7 +608,8 @@
 
             .pub-thumb {
                 width: 100%;
-                height: 160px;
+                aspect-ratio: 1 / 1;
+                height: auto;
             }