Hum, there are various ways to do this. PHP (using cookies to remember the users option) or using javascript. Advantages with PHP is that, the browser won't effect what it does, it will still work the same for everyone using every browser. Javascript, is much eaiser to do, people have example code everywhere, and a quick glanse can do it. Yet, it may not work depending on the users browsers options on displaying javascript.
Flaming Text shows a background changer when you generate a logo. But a PHP example would be, if you made a cookie keep a colour in it, then got the cookie via the varible '$cookie':
code:
<?PHP
echo "<body bgcolor=\"#$cookie\">";
?>
Of course you would need to geerate and fetch a cookie, and that is a bad way of doing it, a very dodgy way indeed, even the html there is not 100% correct. I am not good with cookies, sure I know how to use them, but sercuity is not my strong point + I may of let a flaw slip in.
I would go for javascript. Google is a great way to find some good stuff.
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