下位三角例子
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<div>
</div>
</body>
</html>
<style>
div {
width: 200px;
height: 20px;
border: 1px solid;
position: relative;
transition: all .5s linear;
}
div::after {
position: absolute;
top: 2px;
right: 10px;
content: '';
width: 10px;
height: 10px;
border-bottom: 1px solid red;
display: block;
transform: rotate(45deg);
border-right: 1px solid red;
}
div:hover::after {
transform: rotate(225deg);
top: 8px
}
</style>
标签：伪类,solid,after,1px,10px,div,border,css From： https://www.cnblogs.com/dming4/p/17581231.html