lovecoding
/
Web1020


			
				
					
						
						
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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>
        .div1{
            max-width: 800px;
        }
        .box{
            width: 100%;
            background-color: red;
            padding-top: 50%;
        }
    </style>
</head>
<body>
    <div class="div1">
        <div class="box"></div>
    </div>
    
</body>
</html>