. title{position: relative; width: 100px; height: 50px; line-height: 50px; 文本照明3360中心; background-color: cadetblue; }.title : after { position : absolute; left: 75px; top: 22px; 显示:块; 内容: '; width: 0; height: 0; border :8 pxsolidrgba (0,0,0,0 ); border-top-color:black; }