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<!DOCTYPE html> <html> <head> <meta name="viewport" content="width=device-width, initial-scale=1"> <style> .container { background-color: red; position: relative; width: 100%; padding-top: 100%; /* 1:1 宽高比 */ } .text { position: absolute; top: 0; left: 0; bottom: 0; right: 0; text-align: center; font-size: 20px; color: white; } </style> </head> <body> <h1>保持宽高比 1:1</h1> <p>调整窗口大小可查看效果。</p> <div class="container"> <div class="text">1:1 宽高比</div> </div> </body> </html>