Moving an element: layout vs transform移动元素：改布局还是用 transform

Record a Performance trace, then compare the two buttons. A transform does not change document flow; compositor promotion is browser-dependent.

在 Performance 面板里录制一段记录，再对比两个按钮。transform 不会改变文档流；元素会不会被提升到单独的合成层，取决于浏览器。