CSS——圆角

例子1：

<!DOCTYPE html>
<html lang="en">
<head>
    <style>
        div {
            width: 350px;
            height: 100px;
            padding: 15px 0px 0px 25px;
        }
        .one {
            border-top-left-radius: 2em 0.5em;
            border-top-right-radius: 1em 3em;
            border-bottom-right-radius: 4em 0.5em;
            border-bottom-left-radius: 1em 3em;
            background-color: #CCC;
            margin-bottom: 10px;
        }
        .two {
            border-top-left-radius:2em;
            border-top-right-radius:2em;
            border-bottom-right-radius:2em;
            border-bottom-left-radius:2em;
            background-color: #888;
        }
    </style>   
</head>
<body>
    <div class="one">
        border-top-left-radius: 2em 0.5em;<br>
        border-top-right-radius: 1em 3em;<br>
        border-bottom-right-radius: 4em 0.5em;<br>
        border-bottom-left-radius: 1em 3em;
    </div>
    <div class="two">
        border-top-left-radius:2em;<br>
        border-top-right-radius:2em;<br>
        border-bottom-right-radius:2em;<br>
        border-bottom-left-radius:2em;
    </div>
</body>
</html>

例子2：

<!DOCTYPE html>
<html>
<head>
    <style>
    ul {
        margin: 0;
        padding: 0;
    }
    li {
        list-style: none;
        margin: 10px 0 0 10px;
        padding: 10px;
        width: 200px;
        float: left;
        background: #bbb;
    }
    h2 {
        clear: left;
    }
    .test .one {
        border-radius: 10px;
    }
    .test .two {
        border-radius: 10px 20px;
    }
    .test .three {
        border-radius: 10px 20px 30px;
    }
    .test .four {
        border-radius: 10px 20px 30px 40px;
    }
    .test2 .one {
        border-radius: 10px/5px;
    }
    .test2 .two {
        border-radius: 10px 20px/5px 10px;
    }
    .test2 .three {
        border-radius: 10px 20px 30px/5px 10px 15px;
    }
    .test2 .four {
        border-radius: 10px 20px 30px 40px/5px 10px 15px 20px;
    }
    </style>
</head>
<body>
    <h2>水平与垂直半径相同时：</h2>
    <ul class="test">
        <li class="one">提供1个参数<br>border-radius:10px;</li>
        <li class="two">提供2个参数<br>border-radius:10px 20px;</li>
        <li class="three">提供3个参数<br>border-radius:10px 20px 30px;</li>
        <li class="four">提供4个参数<br>border-radius:10px 20px 30px 40px;</li>
    </ul>
    <h2>水平与垂直半径不同时：</h2>
    <ul class="test2">
        <li class="one">提供1个参数<br>border-radius:10px/5px;</li>
        <li class="two">提供2个参数<br>border-radius:10px 20px/5px 10px;</li>
        <li class="three">提供3个参数<br>border-radius:10px 20px 30px/5px 10px 15px;</li>
        <li class="four">提供4个参数<br>border-radius:10px 20px 30px 40px/5px 10px 15px 20px;</li>
    </ul>
</body>
</html>