<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="renderer" content="webkit">
<title>Title</title>
<style>
.box{
200px;
height: 100px;
border: 2px solid blue;
margin: 100px auto;
position: relative;
border-radius: 20px;
}
.box:before{
content: "";
position: absolute;
0;
height: 0;
top: 36px;
left: -11px;
border-right: 10px solid blue;
border-top: 10px solid transparent;
border-bottom: 10px solid transparent;
}
.box:after{
content: "";
position: absolute;
0;
height: 0;
top: 36px;
left: -8px;
border-right: 10px solid white;
border-top: 10px solid transparent;
border-bottom: 10px solid transparent;
}
</style>
</head>
<body>
<div class="box"></div>
</body>
</html>
Title