Edit styles with input?

Is there any way that I can have multiple textboxes where the user can enter text (such as "black or green") and it would edit a css file, like this:

<style>
body{
background-color:INPUT;
}
</style>

<input type="text" name="bg"/>

?

I don't know that you can change the actual stylesheet with JS, but you can override it with a simple inline statement such as:

<input type="text" name="bgChange" value="" onblur="document.body.style.backgroundColor = this.value;" />


It would be better writing a function though because then you can override a bunch of styles at the same time.