border-radius變為圓形，2個圓形嵌套
<!doctype html>
<style>
body{background:#ccc}
div.line{height:30px;background:#000;position:relative}
div.line div{-moz-border-radius:30px;-webkit-border-radius:30px;border-radius:30px;-khtml-border-radius:30px;background:#000;position:absolute;width:60px;height:60px;left:50%;margin-left:-30px;bottom:0}
div.line div.orange{-moz-border-radius:20px;-webkit-border-radius:20px;border-radius:20px;-khtml-border-radius:20px;background-color:orange;width:40px;height:40px;left:50%;margin-left:-20px;bottom:10px}
</style><br /><br /><br />
<div class="line">
<div></div>
<div class="orange"></div>
</div>
