三角形（css3)

 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: absolute10 }