案例：html/html5 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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<body>
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​
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<p>This is some text. This is some text. This is some text.</p>
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​
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<hr style="width:50%;text-align:left;margin-left:0" />
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​
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<p>This is some text. This is some text. This is some text.</p>
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​
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</body>
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</html>
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​