实现CSS圆环

使用border

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        div{
            width: 200px;
            height: 200px;
            background: brown;
            border: 50px solid greenyellow;
            border-radius: 50%;
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>

View Code

两个嵌套div

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .father{
            width: 200px;
            height: 200px;
            background: greenyellow;
            border-radius: 50%;
        }
        .son{
            width: 100px;
            height: 100px;
            background: brown;
            border-radius: 50%;

            position: relative;
            top: 50px;
            left: 50px;

            /* position: relative;
            top: 50px;
            left: 50px; */
        }
    </style>
</head>
<body>
    <div class="father">
        <div class="son"></div>
    </div>
</body>
</html>

定位

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .father{
            width: 200px;
            height: 200px;
            background: greenyellow;
            border-radius: 50%;
            
            position: absolute;
            /* position: fixed;
            float: left/right;
            overflow: hidden;
            display: inline-block; */
        }
        .son{
            width: 100px;
            height: 100px;
            background: brown;
            border-radius: 50%;
            margin: 50px;
        }
    </style>
</head>
<body>
    <div class="father">
        <div class="son"></div>
    </div>
</body>
</html>

触发父级bfc

使用伪元素，before／after

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        div{
            width: 200px;
            height: 200px;
            background-color: greenyellow;
            border-radius: 50%;
        }
        div::before{
            content: "";
            display: block;
            width: 100px;
            height: 100px;
            border-radius: 50%;
            background-color: brown;

            position: relative;
            top: 50px;
            left: 50px;
            
            /* position: absolute;
            margin: 50px; */
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>

View Code

使用border-shadow

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        div{
            width: 200px;
            height: 200px;
            background-color: greenyellow;
            border-radius: 50%;
            box-shadow: 0 0 0 50px brown inset;
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>

View Code

使用radial-gradient

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        div{
            width: 200px;
            height: 200px;
            border-radius: 50%;
            background: -webkit-radial-gradient( circle closest-side,greenyellow 50%,brown 50%);
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>

径向渐变