<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style>
.triangle {
border: 50px solid red;
width: 0px;
height: 0px;
border-top-color: green;
border-left-color: yellow;
border-right-color: blue;
border-bottom-color: red;
}
</style>
</head>
<body>
<div class="triangle">
</div>
</body>
</html>
