1 .userCard .sanjiao {//三角形的制作； 2 width: 0; 3 height: 0; 4 border-left: 10px solid transparent; 5 border-right: 10px solid transparent; 6 border-bottom: 10px solid rgba(0, 0, 0, .9); 7 margin: -23px 0 0 -10px; 8 left: 50%; 9 position: absolute 10 }
原文：https://www.cnblogs.com/yangguoe/p/9531219.html