User interface themes
The interface theme defines the appearance of windows, dialogs, buttons, and all visual elements of the user interface. By default, CLion uses the Darcula theme, unless you changed it during the first run.
Change the UI theme
In the Settings/Preferences dialog Ctrl+Alt+S, select Appearance & Behavior | Appearance.
Select the UI theme from the Theme list:
IntelliJ Light: Traditional light theme for IntelliJ-based IDEs
macOS Light or Windows 10 Light: OS-specific light theme available as a bundled plugin
Darcula: Default dark theme
High contrast: Theme designed for users with color vision deficiency
Select Sync with OS to let CLion detect the current system settings and use the default dark or light theme accordingly.
It is also possible to create your own UI themes for CLion and customize the built-in themes. For more information, see IntelliJ Platform SDK Documentation.