案例：CSS3 案例     状态：可编辑再运行    进入竖版
 运行结果　
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<!DOCTYPE html>
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<html>
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<head>
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<style>
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input:checked
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{
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background:#ff0000;
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}
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</style>
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</head>
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<body>
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​
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<form action="">
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<input type="radio" checked="checked" value="male" name="gender" /> Male<br>
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<input type="radio" value="female" name="gender" /> Female<br>
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<input type="checkbox" checked="checked" value="Bike" /> I have a bike<br>
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<input type="checkbox" value="Car" /> I have a car
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</form>
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​
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<p><b>注释：</b>本例只在 Opera 中正确地工作！</p>
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​
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</body>
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</html>
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​
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​