<div class="sanjiao" style="width: 0px; height: 0px; border-left-width: 8px; border-left-style: solid; border-left-color: transparent; border-right-width: 8px; border-right-style: solid; border-right-color: transparent; border-bottom-width: 10px; border-bottom-style: solid; border-bottom-color: rgb(100, 100, 100); position: absolute; top: 0px; left: 20px; display: block;"> </div>

css画三角形