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<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>rem的基本使用</title><style>*{padding: 0;margin: 0;}/* 1.给HTML标签加字号 */html{font-size: 30px;}/* 2.使用rem单位书写尺寸 */.box{width: 5rem;height: 3rem;background-color: pink;}</style>
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