看代码吧： XHTML 代码：
<div> <span></span><span></span>
<div>
<p>圆角一</p>
</div>
<span></span><span></span>
</div>
CSS 代码：
.box1 {
background:url(images/bg1.gif) repeat-x #1d6cb7;
margin-top:1em;
position:relative;
zoom:1;
width:778px;
}
.box1 .tl, .box1 .tr, .box1 .bl, .box1 .br {
width:5px;
height:5px;
position:absolute;
background:url(images/bg3.gif) no-repeat;
overflow:hidden;
}
.box1 .cc {
height:40px;
padding:5px;
}
.box1 .tl {
left:0;
top:0;
}
.box1 .tr {
right:0;
top:0;
background-position:0 -5px;
}
.box1 .bl {
left:0;
bottom:0;
background-position:0 -10px;
}
.box1 .br {
right:0;
bottom:0;
background-position:0 -15px;
}
看看上面代码所用到的图片能更好的理解（下面）：
第一部分是左上角的，第二部分是右上角的，第三部分是左下角的，第四部分是右下角的。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>百度有啊css圆角方案</title><style>.box1{background:url('/html/css_yuanjiao/http://demo.jb51.net/html/css_yuanjiao/bg1.gif') repeat-x #1d6cb7;margin-top:1em;position:relative;zoom:1;width:778px;}.box1 .tl,.box1 .tr,.box1 .bl,.box1 .br {width:5px;height:5px;position:absolute;background:url('http://demo.jb51.net/html/css_yuanjiao/bg3.gif') no-repeat;overflow:hidden; }.box1 .cc{height:40px; padding:5px;}.box1 .tl {left:0;top:0;}.box1 .tr {right:0;top:0;background-position:0 -5px;}.box1 .bl {left:0;bottom:0;background-position:0 -10px;}.box1 .br {right:0;bottom:0;background-position:0 -15px;}.box2{border:1px solid #84cedd;margin-bottom:.8em;position:relative;zoom:1;width:778px;}.box2 .tl,.box2 .tr,.box2 .bl,.box2 .br {width:6px;height:6px;position:absolute;background:url('http://demo.jb51.net/html/css_yuanjiao/bg_co1.gif') no-repeat;overflow:hidden;}.box2 .cc{height:40px; padding:5px;}.box2 .tl {left:-1px;top:-1px;}.box2 .tr {right:-1px;top:-1px;background-position:0 -6px;}.box2 .bl {left:-1px;bottom:-1px;background-position:0 -12px;}.box2 .br {right:-1px;bottom:-1px;background-position:0 -18px;}.box3{position:relative;zoom:1;padding:1em 1.5em;margin:.5em 0 1em 0; background:#f1f6de}.box3 .tl,.box3 .tr,.box3 .bl,.box3 .br {width:5px;height:5px;position:absolute;background:url('http://demo.jb51.net/html/css_yuanjiao/bg_co2.gif') no-repeat;overflow:hidden;}.box3 .cc{height:40px; padding:5px;}.box3 .tl {left:0;top:0;}.box3 .tr {right:0;top:0;background-position:0 -5px;}.box3 .bl {left:0;bottom:0;_bottom:-1px;background-position:0 -10px;}.box3 .br {right:0;bottom:0;_bottom:-1px;background-position:0 -15px;}</style></head><body><div><span></span><span></span><div><p>圆角一</p></div><span></span><span></span></div><p></p><div><span></span><span></span><div><p>圆角二</p></div><span></span><span></span></div><p></p><div><span></span><span></span><div><p>圆角三</p></div><span></span><span></span></div></body></html>
提示：您可以先修改部分代码再运行