{
border-color: transparent;
border-right-color: #e5e5e5;
border-width: 7px;
margin-top: -7px;
right: 100%;
top: 20px;
border: solid transparent;
content: " ";
height: 0;
width: 0;
position: absolute;
pointer-events: none;
}
原文：https://www.cnblogs.com/smzd/p/9849736.html