使用border-color:transparent transparent #666 transparent; border-style:dashed dashed solid dashed; border-width:10px;
<html>
<head>
<title>纯CSS无图片带箭头的DIV方框</title>
<style>
div.container{position:absolute;
top:30px;
left:40px;
font-size: 9pt;
display:block;
height:100px;
width:200px;
background-color:transparent;
*border:1px solid #666;
}
s{
position:absolute;
top:-20px;
*top:-22px;
left:20px;
display:block;
height:0;
width:0;
font-size: 0;
line-height: 0;
border-color:transparent transparent #666 transparent;
border-style:dashed dashed solid dashed;
border-width:10px;
}
i{position:absolute;
top:-9px;
*top:-9px;
left:-10px;
display:block;
height:0;
width:0;
font-size: 0;
line-height: 0;
border-color:transparent transparent #fff transparent;
border-style:dashed dashed solid dashed;
border-width:10px;
}
.content{
border:1px solid #666;
-moz-border-radius:3px;
-webkit-border-radius:3px;
position:absolute;
background-color:#fff;
width:100%;
height:100%;
padding:5px;
*top:-2px;
*border-top:1px solid #666;
*border-top:1px solid #666;
*border-left:none;
*border-right:none;
*height:102px;
box-shadow: 3px 3px 4px #999;
-moz-box-shadow: 3px 3px 4px #999;
-webkit-box-shadow: 3px 3px 4px #999;
/* For IE 5.5 - 7 */
filter: progid:DXImageTransform.Microsoft.Shadow(Strength=4, Direction=135, Color='#999999');
/* For IE 8 */
-ms-filter: "progid:DXImageTransform.Microsoft.Shadow(Strength=4, Direction=135, Color='#999999')";
}
</style>
</head>
<body>
<div class="container">
<div class="content"><br>这是框中的文字，可动态显示。高度自动增加，应该不错吧^_^</div>
<s>
<i></i>
</s>
</div>
<br />
</body>
</html>