代码编辑器：
x
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<style>3
*4
{5
background-color:yellow;6
}7
</style>8
<h1>Welcome to My Homepage</h1>9
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<div class="intro">11
<p id="firstname">My name is Donald.</p>12
<p id="hometown">I live in Duckburg.</p>13
</div>14
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<p>My best friend is Mickey.</p>16
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<footer>简单教程，简单编程<br/>Copyright © 简单教程 www.twle.cn</footer>18