边框风格属性(border-style)
这个属性用来设定上下左右边框的风格，它的值如下：
none (没有边框，无论边框宽度设为多大)
dotted (点线式边框)
dashed (破折线式边框)
solid (直线式边框)
double (双线式边框)
groove (槽线式边框)
ridge(脊线式边框)
inset (内嵌效果的边框)
outset (突起效果的边框)
示例：分别使用none,dotted, dashed, solid, double, groove, ridge, inset, outset的CSS边框风格属性示例
<html>
<head>
<title>边框风格属性 border-style </title>
<style type="text/css">
.d1 {border-style:none;}
.d2 {border-style:solid;}
.d3 {border-style:dotted;}
.d4 {border-style:dashed;}
.d5 {border-style:double;}
.d6 {border-style:groove;}
.d7 {border-style:ridge;}
.d8 {border-style:inset;}
.d9 {border-style:outset;}
</style>
</head>
<body>
<div>这个div的CSS边框风格(border-style)属性缺省值是none。</div>
<br>
<div class = "d1">这个div的CSS边框风格(border-style)属性是none。</div>
<br>
<div class = "d2">这个div的CSS边框风格(border-style)属性是solid。</div>
<br>
<div class = "d3">这个div的CSS边框风格(border-style)属性是dotted。</div>
<br>
<div class = "d4">这个div的CSS边框风格(border-style)属性是dashed。</div>
<br>
<div class = "d5">这个div的CSS边框风格(border-style)属性是double。</div>
<br>
<div class = "d6">这个div的CSS边框风格(border-style)属性是groove。</div>
<br>
<div class = "d7">这个div的CSS边框风格(border-style)属性是ridge。</div>
<br>
<div class = "d8">这个div的CSS边框风格(border-style)属性是inset。</div>
<br>
<div class = "d9">这个div的CSS边框风格(border-style)属性是outset。</div>
<br>
</body>
</html>