Want to make the background image or color of your forum a different color/background image when you are at the Portal then it is when you are at the Forum itself?
Easy to do.
At the top of one of your Portal's html blocks add this:
(you dont need to make a new block.. just add it to ONE of the exisiting html blocks)
<style type=text/css>
body
{
background-color: #808080;
background-image: url(IMAGE URL);
}
</style>
Replace #808080 with the color code you want to use
Replace IMAGE URL with the background image url.
If needed add css settings for repeating, position, etc. for the background image.
If you are not using a background image for your forum and are going to only change colors remove this line from the code:
background-image: url(IMAGE URL);