您当前的位置: 下拉菜单模拟效果图：
CSS3：
<style> #box{width:200px; height:50px; overflow:hidden; cursor: pointer; transition: all 0.35s;} #box:hover{height:250px;} #box ul{list-style:none; margin:0; padding:0;} #box ul li{width:198px; height:48px; line-height: 50px; text-align: center; border:1px red solid; background:#000000; color:white;} </style>HTML：
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title></title> </head> <body> <div id="box"> <ul> <li>This's 1</li> <li>This's 2</li> <li>This's 3</li> <li>This's 4</li> <li>This's 5</li> </ul> </div> </body></html>