lovecoding
/
W250511


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box1{
            width: 100px;
            height: 100px;
            background-color: red;
            margin-bottom: 10px;
        }
        .box2{
            width: 100px;
            margin-bottom: 10px;
        }
        .box2::after{
            content: "";
            display: block;
            /* padding 百分比 相较于 父元素宽度 */
            padding-top: 100%;
            background-color: red;
        }

        .box3{
            width: 100px;
            height: 100px;
            position: relative;
        }
        .box3::after{
            content: "";
            display: block;
            position: absolute;
            top:0;
            left: 0;
            right: 0;
            bottom: 0;
            background-color: red;
        }

    </style>
</head>
<body>
    <div class="box1"></div>
    <div class="box2"></div>
    <div class="box3"></div>
</body>
</html>