案例：CSS案例     状态：可编辑再运行    进入竖版
 运行结果　
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<html>
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<head>
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<style type="text/css">
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h1, h2, h3, h4, h5, h6 {
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  color:gray;
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  background: white;
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  padding: 10px;
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  border: 1px solid black;
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  font-family: Verdana;
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  }
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</style>
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</head>
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​
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<body>
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<h1>This is heading 1</h1>
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<h2>This is heading 2</h2>
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<h3>This is heading 3</h3>
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<h4>This is heading 4</h4>
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<h5>This is heading 5</h5>
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<h6>This is heading 6</h6>
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</body>
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</html>
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​