fix(sideMenu): fix disabled menu links

The fix for another issue had too general of a CSS selector, which
ultimately prevented clicks in the left menu when it had a scrollable
area. This fix narrows in the selector so it only prevents
pointer-events in the menu-content’s content area (still allowing the
menu to close by tapping the content, but not allowing the content to
be interacted with, like swiping a list item). Closes #1388

scss/_menu.scss

@@ -24,7 +24,8 @@
   box-shadow: $menu-side-shadow;
 }
 
-.menu-open .scroll-content {
+.menu-open .menu-content .pane,
+.menu-open .menu-content .scroll-content {
   pointer-events: none;
 }