I'm posting to share some custom themes I created to change the appearance of SAS Studio version 3.8x (i.e., 3.8, 3.81, and 3.82). These 3.8x versions of SAS Studio come with a bright white theme and no built-in options to customize it. E.g., there is no dark theme. So I've created a dark theme and a light theme that's not too bright. The themes also make it easy to change the font of the code editor.
Here's a screenshot of the dark theme, called Ignite Dark. It's inspired by the theme of the same name from the SAS Viya versions of SAS Studio. The font for the code in this screenshot is Cascadia Mono; you can set any font that's available on your computer.

The themes can be installed via my github repo here:
https://github.com/dmuenz/sas-studio3-themes
To install one of the themes, you first need a browser extension called Stylus. It's available for Chrome, Edge, and Firefox. Then from my github page you click either "Install Ignite Dark" or "Install Beach Light", and then click the "Install style" button on the top left of your page. The Stylus extension handles the work of applying the custom theme (i.e., custom CSS code) every time you load a SAS Studio tab in your browser.
If you try the themes, let me know if you encounter any issues. I've tried to comb through the entire SAS Studio interface to fully customize the appearance, but I may have missed some features. I also have not tested the themes in SAS Studio 3.81 or in Firefox, since I don't have access to these; if you try them, please let me know how it goes.
I hope you enjoy the themes and find them easy on the eyes!