我如何实现像orkut这样的用户工具来更改网站颜色和样式?

<?php 
//Query database, find the user's colors and create the $bgColor, $leftColor and $topColor variables
?>
<style type="text/css">
<?php echo "body { background-color: $bgColor; }"; ?>
<?php echo "div.left { background-color: $leftColor; }"; ?>
<?php echo "div.top { background-color: $topColor; }"; ?>
</style>

• Rails Giving Each User Their Own Customizable Stylesheet
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