css选择器集体声明
<title>静夜思</title>
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h1,#two,.red{ color:#ff0000; font-size:14px;}
h2,h3{color:#0000ff; font-size:16px; text-decoration:underline;}
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<h1>静夜思</h1>
<h2>床前明月光，</h2>
<p class="red">疑是地上霜。</p>
<h3>举头望明月，</h3>
<p id="two">低头思故乡。</p>
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