To change your theme:
1. Select the dropdown beside your username at the top right and select User Control Panel.
2. Select the Board Preferences tab.
3. From the dropdown beside My board style select a theme from the list.
4. Select Submit at the bottom.
5. Refresh the page and the new theme will appear.
You can do the same to switch it back. The current "default" is called "Lucid Lime" (I never changed the name from the template I based it on ahaha
)Also a disclaimer: If you're thinking of contributing a theme, I just want to mention that phpBB has a specific format for their themes, based on PHP with tons of files. Because of that, it's not as easy as slapping in custom CSS - some changes may not go through.
