定宽高的水平垂直居中

绝对定位和负magin值

效果预览

<div class="parent"> <div class="child"></div> </div> div.parent { width: 400px; height: 400px; background: #EDEDED; position: relative; } div.child { width: 200px; height: 200px; background: green; position: absolute; left: 50%; top: 50%; margin-left: -100px; margin-top: -100px; }

绝对定位 + left/right/bottom/top + margin

div.parent { width: 400px; height: 400px; background: #EDEDED; position: relative; } div.child { width: 200px; height: 200px; background: green; position: absolute; left: 0; top: 0; bottom: 0; right: 0; margin: auto; }

flex

这种方法在不定宽高的时候也可以使用，页面结构如上，效果预览

div.parent { width: 400px; height: 400px; background: #EDEDED; display: flex; justify-content:center; align-items: center; } div.child { width: 300px; height: 200px; background: green; }

绝对定位+transform

这个方法在不定宽高中也使用过，页面结构不变，效果预览

div.parent { width: 400px; height: 400px; background: #EDEDED; position: relative; } div.child { width: 100px; height: 100px; position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); background: green; }

table-cell + vertical-align + inline-block

先提醒一下，vertical-align的值是middle，而不是center

页面结构不变，效果预览

div.parent { width: 400px; height: 400px; background: #EDEDED; display: table-cell; text-align: center; vertical-align: middle; } div.child { width: 100px; height: 100px; display: inline-block; background: green; }