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<html lang="en"><head> <meta charset="UTF-8"> <title>外部样式表css</title> <link rel="stylesheet" type="text/css" href="style.css"></head><body><details> <summary>样式的三种方法</summary> <ol> <li>内联</li> <li>内部</li> <li>样式表</li> </ol> </details><p>这是一个例子</p></body></html>