圆角

一个转动的风筝小demo
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .box{
            width: 400px;
            height:400px;
            margin: 50px auto;
            transition: 5s linear;
        }
        .box div{
            width: 180px;
            height: 180px;
            margin: 10px;
            border:1px solid #000;
            box-sizing: border-box;
            float: left;
            background:linear-gradient(to bottom right, blue, white);/*线性渐变背景*/
            
        }
        .box div:nth-child(1),.box div:nth-child(4){
            border-radius: 0 70%;/*圆角的改变用百分比表示*/
        }
        .box div:nth-child(3),.box div:nth-child(2){
            border-radius: 70% 0;
        }
        .box:hover{
            -webkit-transform: rotate(720deg);/*鼠标移入旋转多少度*/
        }
    </style>
</head>
<body>
    <div class="box">
        <div></div>
        <div></div>
        <div></div>
        <div></div>
    </div>
</body>
</html>
运行结果为：
鼠标移入后会旋转：