trilium/docs/Developer Guide/Developer Guide/Development and architecture/Themes.md

Themes

Server-side

• There are three themes embedded in the application:
  • light, located in src\public\stylesheets\theme-light.css
  • dark, located in src\public\stylesheets\theme-dark.css
  • next, located in src\public\stylesheets\theme-next.css.
• The default theme is set only once, when the database is created and is managed by options_init#initNotSyncedOptions.
  • In the original implementation: On Electron, the choice between light and dark is done based on the OS preference. Otherwise, the theme is always dark.
  • Now, we always choose next as the default theme.
• The theme is served via src\routes\index.ts, in the getThemeCssUrl method.

Client-side

• The predefined themes are hard-coded in the client in src\public\app\widgets\type_widgets\options\appearance\theme.js.
• The user-defined themes are obtained via a call to the server: options/user-themes.
• The theme retrieval is done via a request.