No functional changes, but the themes available on Tildes itself now transfer over to the Blog/Docs sites (previously those sites were always using the "Solarized Light" color scheme). It was a little painful before if you were using a dark theme and clicking something like the "Formatting help" link took you to a bright page, so this should be a lot better.
There's currently no way to select a theme from the other sites, just on Tildes itself, but it should carry over when you've selected one here (using the dropdown in the footer if you're logged out, or through the settings page if you're logged in).
Please let me know if you come across any issues with it. It was pretty straightforward overall, but it did involve redoing a lot of the CSS and HTML for the Blog/Docs sites, so it's very possible that I messed some pages up and haven't noticed yet.