GitClear offers site-wide themes for light or dark mode. To control which mode is used, hover on "[your name]'s Account" in the upper right, and then pick "Account Settings" from the dropdown. The theme colors are located under the "Preferences" tab once you're visiting your Account Settings.

Choosing "Light theme" or "Dark theme" will result in GitClear's side-wide experience remaining fixed to light or dark. Choose the "Dynamic theme" if you'd rather have GitClear switch between light and dark modes based on your OS settings.