<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>吉结号</title>
<link rel="shortcut icon" href="image/g3.ico">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script>
<style>
body{
margin: 0;
padding: 0;
background: url("2.png") center center no-repeat;
}
.zz:after{
position: absolute;
top: 0;
left: 0;
content: "";
background-color: blue;
opacity: 0.2;
z-index: 1;
width: 100%;
height: 100%;
}
</style>
</head>
<body>
<div class="zz">
<div><h1>content</h1></div>
</div>
</body>
</html>