通过CSS3中的伪元素实现折叠
<!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="Generator" content="EditPlus®"> <meta name="Author" content=""> <meta name="Keywords" content=""> <meta name="Description" content=""> <title>Document</title> <style type="text/css"> *{padding:0px;margin:0px;background:#fff;} .container{width:500px;height:300px;background-color:#36B11D;margin:100px auto;border-radius:10px;position:relative;-moz-border-radius:10px;-webkit-border-radius:10px;-ms-border-radius:10px;-o-border:40px solid #7201AA;} .container:before{position:absolute;left:0px;top:0px;content:"";background:#fff;display:block;border:40px solid #7201AA;-webkit-border:40px solid #7201AA;-moz-border:40px solid #7201AA; -ms-border:40px solid #7201AA;-o-border:40px solid #7201AA;border-color:transparent rgba(0,255,0,.5) rgba(0,220,0,.5) transparent;-moz-border-color:transparent rgba(0,255,0,.5) rgba(0,220,0,.5) transparent;-webkit-border-color:transparent rgba(0,255,0,.5) rgba(0,220,0,.5) transparent;-ms-border-color:transparent rgba(0,255,0,.5) rgba(0,220,0,.5) transparent;-o-border-color:transparent rgba(0,255,0,.5) rgba(0,220,0,.5) transparent; } .container:after{position:absolute;right:0px;top:0px;width:0px;content:"";border:40px solid #7201AA;background-color:#fff;-webkit-border:40px solid #7201AA;-moz-border:40px solid #7201AA; -ms-border:40px solid #7201AA;-o-border:40px solid #7201AA;-moz-border-color:transparent transparent rgba(0,220,0,.5) rgba(0,255,0,.5); -ms-border-color:transparent transparent rgba(0,220,0,.5) rgba(0,255,0,.5);-webkit-border-color:transparent transparent rgba(0,220,0,.5) rgba(0,255,0,.5); border-color:transparent transparent rgba(0,220,0,.5) rgba(0,255,0,.5);box-shadow:-1px 1px 1px rgba(0,0,0,.5);-webkit-box-shadow:-1px 1px 1px rgba(0,0,0,.5);-ms-box-shadow:-1px 1px 1px rgba(0,0,0,.5);-moz-box-shadow:-1px 1px 1px rgba(0,0,0,.5);-o-box-shadow:-1px 1px 1px rgba(0,0,0,.5);} </style> </head> <body> <div class="container"></div> </body> </html>