<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
div{
width:300px;
}
.box{height:300px;margin:0 auto;position:relative;}
.content{height:300px;background-color: blue;position: absolute;left:-5px;top:-5px;z-index:1;}
.mark{height:300px;background-color: #000;position: absolute;left:5px;top:5px;opacity:0.5;}
/*
z-index z轴 提升层级
opacity 透明度 0完全透明 1完全不透明
*/
</style>
</head>
<body>
<div class="box">
<div class="content"></div>
<div class="mark"></div>
</div>
</body>
</html>
[ 此帖被一支穿云箭 在2018-05-04 20:54重新编辑 ]
