fix Menu bar shakes when swiping pages in Safari

src/theme/css/chrome.css

@@ -16,13 +16,15 @@ a > .hljs {
     body-container is necessary because mobile browsers don't seem to like
     overflow-x on the body tag when there is a <meta name="viewport"> tag.
 */
-#body-container {
+@media only screen and (max-width: 420px) {
+    #body-container {
         /*
             This is used when the sidebar pushes the body content off the side of
             the screen on small screens. Without it, dragging on mobile Safari
             will want to reposition the viewport in a weird way.
         */
         overflow-x: clip;
+    }
 }
 
 /* Menu Bar */