网页制作中边框的倒圆角怎么操作呢

网页制作中边框的倒圆角怎么操作呢？
网页制作中边框的倒圆角怎么操作呢？

img

https://blog.51cto.com/u_15127645/4324785

给div价格样式


.leftB {
    left: -50px;
    bottom: -50px;
}


<html>
<head>
<meta charset="utf-8"/>
<title></title>
<style type="text/css">
.cro{
    width: 100px;
    height: 100px;
    border: 1px solid #58C4E6;
    position: relative;
}
.cro_left_bottom{
    position: absolute;
    width: 20px;
    height: 20px;
    border: 1px solid #fff;
    z-index: 1;
    background: #fff;

    left: -1px;
    bottom: -1px;
    border-radius:0px 20px 0px 0px;
    border-top: 1px solid #58C4E6;
    border-right: 1px solid #58C4E6;
}
</style>
</head>
<body>
<div class="cro">
        <div class="cro_left_bottom"></div>
</div>
</body>
</html>

左下角就是右上角