<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>百度</title></head><body> <div id="top"; style=" width:740px;margin:0 auto;"><img src="bdlogo.png"/></div> </body></html>它不在中间啊,如果不指定宽度它就在左侧了
试试这个方案xximg