table + margin 实现水平方向居中, table-cell + vertical-algin 实现垂直居中
<!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>居中布局(水平居中+垂直居中)的第一种解决方案</title>
<style>
#parent {
width: 1000px;
height: 600px;
background: #ccc;
/* <td> */
display: table-cell;
vertical-align: middle;
}
#child {
width: 200px;
height: 200px;
background: #c9394a;
/* <table> */
display: block;
margin: 0 auto;
}
</style>
</head>
<body>
<!-- 定义父级元素 -->
<div id="parent">
<!-- 定义子级元素 -->
<div id="child"></div>
</div>
</body>
</html>