## 给唯一子元素margin-top，父元素跟随移动 ~~~ .parent{ background: darkslateblue; width: 400px; height: 400px; /* overflow: hidden; */ } .child{ background: salmon; width: 100px; height: 100px; margin-top: 100px; } ~~~ ~~~ <div class="parent"> <div class="child"></div> </div> ~~~  **解决方案：** 1.**伪元素** ~~~ .parent::before{ display: table; content: ""; } ~~~ 2.**给父元素overflow:hidden**