Hi @mauric,
The best way to browse themes is vscodethemes.com. Just keep in mind that many themes have not been tweaked for Elixir. If you like the default dark theme, there is an Elixir-friendly version called Dark+ Elixir that is popular around here. We also had a recent poll on VS Code themes (EDIT: looks like Axelson already mentioned this…a good starting point, in any event). I am using my own theme, called Yarra Valley. Good luck!
