OBS Studio has the ability to load different themes based on your needs. The option is available in Settings -> General.

Default themes includes:

• Acri - designed by Warchamp7
• Dark - the default theme since OBS 21.0
• Default - the System-based theme
• Rachni - designed by Fenrir

The files for the default themes can be found in the OBS Studio installation directory, specifically /data/obs-studio/themes/

Installing custom themes

The best place to install custom themes is in your user directory - the same place where profiles and scenes are stored, so that if you ever reinstall OBS Studio, you don't lose your custom themes.

• Windows: WinKey+R > %APPDATA%\obs-studio\themes\
• macOS: Cmd+Shift+G > ~/Library/Application Support/obs-studio/themes/
• Linux: ~/.config/obs-studio/themes/

You may have to create the themes directory yourself.
You can find themes created by members of the community at this link.

Designing your own theme

Themes use a combination of something called QSS and a folder of custom images.

QSS is based on a subset of CSS2, and its documentation is all over the place.
It's recommended to open one of the default themes (Rachni has great documentation) and use it as a reference.

Documentation for QSS is split up quite heavily, but here are the links you will need:

• The Style Sheet Syntax - covers the basics on how to write QSS
• Qt Style Sheets Reference - lengthy documentation on which widgets can be customized, and how, including pseudo-states and sub-controls