Themes for Kazeta+.
Download any of the available themes on the Releases page. Extract the archive to ~/.local/share/kazeta-plus/themes/. From there, you can change the theme in Kazeta+ by going to Settings. (Or, just use the theme downloader directly from the BIOS.)
Easily create your own themes with KZI Cartridge Generator.
Interested in submitting your own theme? Submit a pull request.