CSS-类选择器案例.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>利用类画三个颜色的盒子</title>
    <style>
        /* 多类名减少重复代码 */
        .box {
            width: 100px;
            height: 100px;
        }
        .red {
            width: 100px;
            height: 100px;
            /* 背景颜色 */
            background-color: red;
        }
        .black {
            width: 100px;
            height: 100px;
            /* 背景颜色 */
            background-color: black;
        }
        .green {
            /* 背景颜色 */
            background-color: green;
        }
    </style>
</head>
<body>
    <div class="red"></div>
    <div class="green box"></div>
    <div class="black"></div>
    <div class="green box"></div>
</body>
</html>