直奔主题在这里提供三种块级元素垂直水平居中的方法

  1. flex（子级宽高可固定也可不固定，随意）
  2. 定位+margin（固定子级的宽高，margin-top,margin-left取自身一半的负值）
  3. 定位+transform（不固定子级的宽高）

flex

html<div class="parent">    <div class="child"></div></div>css.parent{    width: 500px;    height: 500px;    margin: 0 auto;    border: 1px solid gainsboro;    display: flex;    justify-content: center;    align-items: center;}.child{    width: 200px;    height: 200px;    background: red;}

定位+margin

html<div class="parent">    <div class="child"></div></div>css.parent{        position: relative;        width: 500px;        height: 500px;        margin: 0 auto;        border: 1px solid gainsboro;    }.child{        position: absolute;        top: 50%;        left: 50%;        width: 200px;        height: 200px;        margin-left: -100px;        margin-top: -100px;        background: red;    }

定位+transform

html<div class="parent">    <div class="child">        <span>我是子元素</span>    </div></div>css.parent{        position: relative;        width: 500px;        height: 500px;        margin: 0 auto;        border: 1px solid gainsboro;    }    .child{        position: absolute;        top: 50%;        left: 50%;        transform: translate(-50%,-50%);        background: red;    }

个人更喜欢flex

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