As on our old software, we have a few different themes to choose from.
For users coming from the homepage, click on the X comments line below for further information.
To change your theme, log in to the board and click on the Profile button which will then show a list of options along the left side, about halfway through that list is "Look and Layout Preferences". Near the top of that page is "Current Theme:" with a theme name shown and a change button. It's as simple as that, it even shows you a small thumbnail image of what the theme looks like.
:)