<!DOCType html>
<html>
<head>
<meta charset="utf8" />
<style type="text/css">
.tip {
position:relative;
margin-left:4px;
background-color:#ff4500;
padding-left:5px;
height:18px;
line-height:18px;
font-size:12px;
color:#fff;
}
.tip .arrow{
border-top:4px solid #fff;
border-bottom:4px solid #fff;
border-right:4px solid #ff4500;
line-height:0px;
position:absolute;
left:-4px;
top:5px;
}
</style>
</head>
<body>
<div class="tip">
<div class="arrow"></div>
<label>这是个提示</label>
</div>
</body>
</html>
效果：
原文：http://my.oschina.net/honchy/blog/394438