Dynamic css files using scss

I'm trying change the value of a scss variable dynamically using rails
3.1.

For example:

In a example.css.scss

$main-color: red;
body {
  background-color: $main-color;
  color: #333;
  font-family: verdana, arial, helvetica, sans-serif;
  font-size: 13px;
  line-height: 18px; }

And in the model user, I put the field color_prefered. And I want to
change the value of a $main-color with the value of user.color_prefered.

Is it possible?

Tk.
Rafa.

This is a heck of a lot easier to do in the presentation than the style. Consider this:

body
  .red
    background-color: red
  .green
    background-color: green

<body class="<%= @theme_main_color %>">
  Stuff inside
</div>

In your controller (or application controller), simply set @theme_main_color to whatever you want.