You can, go to the very bottom of the main page on the left side you'll see a drop down box with "Synapse sytle" and "scarlet_x" and you can turn the forum into a scarlet color.

The problem with this is that it's light font against dark backgrounds which after long periods of time strains the eyes.

I used to be permanent, but most agreed dark fonts on light background was better so the Admin made it an option.