1. Margins can align block-level boxes in the center, but two conditions must be met
(1) The box must specify a width (width)
(2) The left and right margins of the box are set to auto
2. Code:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>块级盒子水平居中对齐</title>
<style>
.header{
width: 900px;
height: 200px;
background-color: pink;
margin: 0 auto;
}
</style>
</head>
<body>
<div class="header"></div>
</body>
</html>The most common way to write: margin: 0 auto
3. Operation effect:
