ルールビュー で transform プロパティにマウスポインターを載せると、ページ上に変形操作をオーバーレイ表示します:
MDN will be in maintenance mode for a brief period Wednesday June 3, from around 2:30 PM until no later than 4:00 PM Pacific (in UTC, Wednesday June 3, 9:30 PM to 11:00 PM). There should be no disruption in service.