Down Triangle CSS

<!DOCTYPE html>
<html>

<head>
     <style>
.down-triangle {
   border-left: 100px solid transparent;
   border-right: 100px solid transparent;
   border-top: 172px solid green;
   width: 0;
}
     </style>
</head>

<body>
   <div class="down-triangle"></div>
</body>

</html>