关于CSS3新增的一个属性实现水平垂直居中

August 25, 2019

1928 views

692 words

calc
abbr.计算;

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    .father {
      width: 800px;
      height: 800px;
      background-color: blue;
      position: relative;
    }

    .son {
      width: 200px;
      height: 200px;
      background: yellow;
      position: absolute;
      top: calc(50% - 100px);
      left: calc(50% - 100px)
    }
  </style>
</head>

<body>
  <div class="father">
    <div class="son"></div>
  </div>
</body>

</html>

这个方法是用定位走50%然后再走自身的一半实现居中，但是这个calc函数直接用一行就能实现计算出最终要走的数值，正常加减乘除都能正常使用

下面是标准语法说明

calc( <calc-sum> )
where 
<calc-sum> = <calc-product> [ [ '+' | '-' ] <calc-product> ]*

where 
<calc-product> = <calc-value> [ '*' <calc-value> | '/' <number> ]*

where 
<calc-value> = <number> | <dimension> | <percentage> | ( <calc-sum> )

具体说明请查看MD
MDN