Recaf comes with 2 themes; a flat dark style and the default JavaFx modena style. Each theme is split into two parts:

Adding custom themes

To add your own themes navigate to the Recaf config directory (See: Config). In this directory are there is a "style" sub-directory. In the style directory you can add window and text styles by creating ui-THEME_NAME.css and text-THEME_NAME.css respectively. You may want to copy an existing theme from the Recaf source code as a basis to work off of.

Using the theme editor

The theme editor is a heavy work-in-progress. To open it, install the theme plugin (Released in the Recaf Discord server) then launch Recaf. Under the plugins menu you will find a menu item for the theme editor, which will open the editor window. When working in this editor the theme file ui-custom.css is written to after each modification. Additionally, the UI styles are reloaded after modifications so that it can be reloaded dynamically. To see the changes live, make sure you set the window theme to "Custom".

See also: JavaFX CSS Reference Guide