无图片实现圆角框
<style type="text/css">div.RoundedCorner{background: #9BD1FA}b.rtop, b.rbottom{display:block;background: #FFF}b.rtop b, b.rbottom b{display:block;height: 1px;overflow: hidden; background: #9BD1FA}b.r1{margin: 0 5px}b.r2{margin: 0 3px}b.r3{margin: 0 2px}b.rtop b.r4, b.rbottom b.r4{margin: 0 1px;height: 2px}</style><div class="RoundedCorner"><b class="rtop"><b class="r1"></b><b class="r2"></b><b class="r3"></b><b class="r4"></b></b><br>无图片实现圆角框<br><br><b class="rbottom"><b class="r4"></b><b class="r3"></b><b class="r2"></b><b class="r1"></b></b></div>?