<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>DEMO</title>
<style>
.demo{
width: 200px;
height: 200px;
/*background-color: #999;*/
margin: 0 auto;
}
.tri{
display: block;
width: 20px;
height: 20px;
position: relative;
left: 10px;
/*border: 1px solid green;*/
}
.tri:before,.tri:after{
content: "";
display: block;
position: absolute;
left: 0;
top: 0;
border-width: 10px;
border-color: transparent transparent red transparent;
border-style: dashed dashed solid dashed;
}
.tri:after{
margin-top: 1px;
border-color: transparent transparent white transparent;
}
.tri.active:before{
border-color: transparent transparent green transparent;
}
</style>
</head>
<body>
<div class="demo">
<span class="tri active"></span>
</div>
</body>
</html>