Penggunaan praktikal teg CSS + <em> untuk melengkapkan penghasilan pertukaran triangle_Experience

<meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <title>Gunakan tag CSS + <em> untuk melengkapkan penghasilan segi tiga</em> </title> <style type="text/css"> <!-- #menu {width:500px;padding:0;margin:40px auto;list-style-type:none;display:table;} #menu li {width:100px; float:left; line-height:30px} #menu a {position:relative;display:block; text-decoration:none; background:#cccccc;width:100px; } #menu a span {display:block; font-weight:bold;color:#000; border-style:solid;border-width:0px 2px 2px 0px; border-color:#fff #fff #06a #fff;text-align:center; }#menu a em {display:none;} #menu a:hover {background:#FF0000;}#menu a:hover span {color:#fff; } #menu a:hover em {display:block; overflow:hidden; border:6px solid #06a; border-color:#06a #fff; border-width:6px 6px 0 6px; position:absolute; left:50%; top:100%;margin-left:-6px;} --> </style> <ul id="menu"> <li><a href="#nogo"><span>M One</span><em></em></a></li> <li><a href="#nogo"><span>M Dua</span><em></em></a></li> <li><a href="#nogo"><span>M Tiga</span><em></em></a></li> <li><a href="#nogo"><span>M Empat</span><em></em></a></li> </ul>