<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> <style type="text/css"> .triangle_border_up{ display:block; 0; height:0; border-0 10px 10px; border-style:solid; border-color:transparent transparent #fc0;/*透明 透明 黄*/ position:absolute; top:0px; left:0px; } .triangle_border_down{ display: block; 0; height: 0; border- 9px 9px 0; border-style: solid; border-color: #fc0 transparent transparent; position: absolute; top: 16px; left: 10%; } .triangle_border_left{ display:block; 0; height:0; border-8px 8px 8px 0; border-style:solid; border-color:transparent #fc0 transparent transparent;/*透明 黄 透明 透明 */ position:absolute; top:0px; left:36%; } .triangle_border_right{ display:block; 0; height:0; border-8px 0 8px 8px; border-style:solid; border-color:transparent transparent transparent #fc0;/*透明 透明 透明 黄*/ position:absolute; top:0px; left:70%; } </style> </head> <body> <span class="triangle_border_up"></span> <span class="triangle_border_down"></span> <span class="triangle_border_left"></span> <span class="triangle_border_right"></span> </body> </html>