参考了天猫、微博等网站的做法，用纯html和css实现，效果还是不错的。
以下是成果，兼容主流浏览器，包括ie6。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv="Content-Language" content="zh-CN" />
<meta name="Keywords" content="" />
<meta name="Description" content="" />
<title></title>
</head>
<style type="text/css">
*{margin:0; padding:0; list-style:none; font:normal 12px/150% 宋体; }
body{ padding:20px; }
.arrow{ margin-bottom:20px; }
/* css三角形 */
.arrow,.arrow s { position:relative; display:block; font-size: 0; line- height: 0; width: 0; height: 0; border-color:transparent; border-style:dashed; border-width:5px; }
.arrowR,.arrowR s{ border-left-color:#aaa; border-left-style:solid; }
.arrowR s{ border-left-color:#fff; position:absolute; left:-7px; top:-5px; }
.arrowR:hover{ border-left-color:#f60; }
.arrowL,.arrowL s{ border-right-color:#aaa; border-right-style:solid; }
.arrowL s{ border-right-color:#fff; position:absolute; right:-7px; top:-5px; }
.arrowL:hover{ border-right-color:#f60; }
.arrowT,.arrowT s{ border-bottom-color:#aaa; border-bottom-style:solid; }
.arrowT s{ border-bottom-color:#fff; position:absolute; left:-5px; top:-3px; }
.arrowT:hover{ border-bottom-color:#f60; }
.arrowB,.arrowB s{ border-top-color:#aaa; border-top-style:solid; }
.arrowB s{ border-top-color:#fff; position:absolute; left:-5px; bottom:-3px; }
.arrowB:hover{ border-top-color:#f60; }
/* css圆形 */
.circle{ line-height:100%; overflow:hidden; font- family:Tahoma,Helvetica; font-size:18px; color:#aaa; }
.circle:hover{ color:#f60; }
/* 提示盒子 */
.tipBox{ width:200px; margin-top:10px; }
.tipBox .hd{ height:5px; position:relative; }
.tipBox .hd .arrow{ position:absolute; top:-5px; left:10px; }
.tipBox .hd .arrow s{ top:-4px; }
.tipBox .bd{ border:1px solid #aaa; padding:10px; -webkit-border- radius:5px; -moz-border-radius:5px; border-radius:5px; }
.tipBoxA .arrow s{ border-bottom-color:#f6f6f6; }
.tipBoxA .bd{ background:#f6f6f6; }
</style>
<body>
<a class="arrow arrowR"></a>
<a class="arrow arrowL"></a>
<a class="arrow arrowT"></a>
<a class="arrow arrowB"></a>
<a class="arrow arrowR"><s></s></a>
<a class="arrow arrowL"><s></s></a>
<a class="arrow arrowT"><s></s></a>
<a class="arrow arrowB"><s></s></a>
<a class="circle">•</a>
<div class="tipBox">
<div class="hd">
<s class="arrow arrowT"><s></s></s>
</div>
<div class="bd">
用css做的提示盒子，上三角是纯css，盒子圆角用到css3
</div>
</div>
<div class="tipBox tipBoxA">
<div class="hd">
<s class="arrow arrowT"><s></s></s>
</div>
<div class="bd">
用css做的提示盒子，上三角是纯css，盒子圆角用到css3
</div>
</div>
</body>
</html>
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