css3-伪元素before,after
2019-08-26 本文已影响0人
AssertDo
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>伪元素：::before ::after</title>
<style>
*{
padding: 0;
margin: 0;
}
body{
padding: 200px;
}
div:nth-of-type(1){
width: 300px;
height: 200px;
background-color: red;
float: left;
}
div:nth-of-type(2){
width: 100px;
height: 200px;
background-color: blue;
float: left;
position: relative;
}
div:nth-of-type(2)::before{
/*必须添加content属性，否则后期不可见*/
content: "";
/*默认是行级元素，如果想设置宽高，就必须转换为块级元素*/
position: absolute;
width: 20px;
height: 20px;
background-color: #fff;
border-radius: 10px;
left: -10px;
top: -10px;
}
div:nth-of-type(2)::after{
/*必须添加content属性，否则后期不可见*/
content: "";
/*默认是行级元素，如果想设置宽高，就必须转换为块级元素*/
position: absolute;
width: 20px;
height: 20px;
background-color: #fff;
border-radius: 10px;
left: -10px;
bottom: -10px;
}
</style>
</head>
<body>
<div></div>
<div></div>
</body>
</html>
