1、举个例子<!DOCTYPE html><html><head> <title>wheel</title> <style type="text/css" > #sample{ width: 900px; height: 600px; position: absolute; margin: 0,auto; background: #A5A5A5; } </style></head><body id="body"> <div id="sample"> </div></body></html>在这里，虽然css有margin: 0,auto;，显示效果如下图所示，没有居中
