<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
/*第一种垂直水平居中*/
.father{
width: 300px;
height: 300px;
background: red;
display: table-cell;
vertical-align: middle;
}
.child{
width: 100px;
height: 100px;
margin:0 auto;
}
/*第二种垂直水平居中*/
.father{
display: flex;
justify-content: center;
align-items: center;
width: 300px;
height: 300px;
background: red;
}
.child{
width: 100px;
height: 100px;
}
/*第三种垂直水平居中*/
.father{
width: 300px;
height: 300px;
background: red;
position: relative;
}
.child{
width: 100px;
height: 100px;
position: absolute;
left: 0;
top: 0;
right: 0;
bottom: 0;
margin: auto;
}
/*第四种垂直水平居中*/
.father{
width: 300px;
height: 300px;
background: red;
position: relative;
}
.child{
width: 100px;
height: 100px;
position: absolute;
left: 50%;
top: 50%;
margin-top: -50px; /* 高度的一半 */
margin-left: -50px; /* 宽度的一半 */
}
</style>
</head>
<body>
<div class="father">
<div class="child">123</div>
</div>
</body>
</html>
原文：https://www.cnblogs.com/1rookie/p/12008276.html