<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.father{
border-color: red;
border-width: 2px;
border-style: solid;
margin: 0 auto;
margin-top: 50px;
height: 200px;
width: 400px;
}
.father .child{
margin: 0% auto;
margin-top: 10%;
width: 0px;
height: 0px;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-top: 60px solid red;
}
</style>
</head>
<body>
<div class="father">
<div class="child"></div>
</div>
</body>
</html>
