ui: better mobile review-box sizing (#10297)

web_src/less/_review.less

@@ -132,3 +132,14 @@
 .ui.blob-excerpt:hover {
     color: #428bca;
 }
+
+@media only screen and (max-width: 768px) {
+    #review-box > .menu {
+        > .ui.segment {
+            width: 94vw;
+        }
+        .editor-toolbar {
+            overflow-x: auto;
+        }
+    }
+}