<div class="box">
</div>
.box {
width: 0;
height: 0;
background: transparent;
border-top: 10px solid transparent;
border-left: 10px solid transparent;
border-right: 10px solid #00BBFF;
border-bottom: 10px solid #00BBFF;
}
This Pen doesn't use any external CSS resources.
This Pen doesn't use any external JavaScript resources.