<div class="arrow_down"></div>
.arrow_down {
width: 0;
height: 0;
border-left: 4px solid transparent;
border-right: 4px solid transparent;
border-top: 4px solid #008fd4;
}
<div class="arrow_down"></div>
.arrow_down {
width: 0;
height: 0;
border-left: 4px solid transparent;
border-right: 4px solid transparent;
border-top: 4px solid #008fd4;
}