[DaRK mAN306]

Hello there smartkidbk5,

Well, I don't think that it's possible to add template variables into the CSS templates except for the "{vb: stylevar <stylevar name>}" .!

To solve that problem, we're going to move the "html" CSS code from "vbulletin.css" to "headinclude" if it's OK with you !!

In order to do that you can follow these step-by-step instructions:

1. First of all, sign into your Admin CP ..
2. Then, go to "Styles & Templates >> Style Manager" ..
3. After that, choose "Edit Templates" option from your defined vB Style drop-down menu ..
4. Then, Expand the template groups and look for "vbulletin.css" template and edit it ..
5. Once you enter the template, look for:

   html {
       background:{vb:stylevar doc_background};
   }

   Then delete it from the template and don't forget to "save" it .!
6. After doing that, go to "headinclude" template and add this code in the end of it:

   <style type="text/css">
   <!--
   html {
       background:rgb(0, 0, 0) url({vb:raw bbuserinfo.fieldX}) no-repeat  fixed center top;
   }
   -->
   </style>

   Don't forget to change the text in RED(X) to your field ID which is 17 as you posted .!
7. "Save" the template and go check out your custom BG background .!

That should do the trick .!
BTW, I've already tested the method and it works like CHARM !!