A collection of themes for Serious.
Go to the releases page and download the one you want. Unzip the archive and replace the theme.css file in your Serious output folder with the downloaded version.
Delete the theme.css file from your output folder. When you run the build command again, a blank one will be generated.
Feel free to fix up things via pull requests or let me know about stuff via issues.
If you want to contribute themes, you can edit your theme.css file to your liking, then send me a link or the file. If you send me a file, let me know how you're licensing it, how you want to be credited, and what your theme should be called.