FIX: topic-admin-popup-menu was overflowing on small screens (#9944)

app/assets/stylesheets/mobile/topic.scss

@@ -221,29 +221,24 @@ sub sub {
 @media screen and (max-height: 600px) {
   .topic-admin-popup-menu {
     box-sizing: border-box;
-    width: 100%;
-    padding: 1em;
-    .header {
-      padding: 0;
-      position: relative;
-      .close-button {
-        position: absolute;
-        display: inline-block;
-        right: 0;
-        top: -0.1em;
-        width: auto;
-        background: transparent;
-      }
-    }
+    padding: 0.25em;
+
     ul {
       display: grid;
       grid-template-columns: 1fr 1fr 1fr;
+
       @media screen and (max-width: 550px) {
         grid-template-columns: 1fr 1fr;
       }
+
       .popup-menu-btn {
         @include ellipsis;
       }
+
+      li {
+        border: 0;
+        min-width: 0;
+      }
     }
   }
 }