鼠标移入能看到效果
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title></title> <style type="text/css"> .d1{width: 200px; height: 200px; background: green; position: relative; overflow: hidden; } .d2{width: 200px; height: 200px; z-index: 1; position: absolute; } .d2:before{content: ""; position: absolute; width: 100%; height: 100%; top: 100%; background: red; z-index: -2; transition: all 0.5S linear;} .d2:hover:before{top: 0%} </style> </head> <body> <div class="d1"> <div class="d2">给我一个渐变的效果</div> </div> </body> </html>
原文：http://www.cnblogs.com/alasq/p/5894840.html