row

row hover

HTML

<link rel="stylesheet" href="http://getbootstrap.com/dist/css/bootstrap.css">
<div class="triangle-down">

</div>

CSS

.triangle-down {
    width: 0;
    height: 0;
    border-left: 51.43px solid transparent;
    border-right:  51.43px solid transparent;
    border-top: 50px solid red;
}