有关于margin的一点东西！
这里我要说一下css外容器margin的问题！先看看下面的例子，<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>Demo-1</title><style type="text/css">#wrapper{border:1px #999 solid; width:600px; margin-bottom:20px;}.left{width:300px; float:left; height:100px; background:red;}.right{width:300px; float:left; height:300px; background:#ccc;}#footer{clear:both;width:600px;height:20px; background:#000;border:1px solid #ccc;}</style></head><body><div id="wrapper"> <div class="left"></div> <div class="right"></div></div><div id="footer"></div></body></html>