Modify the Google Calendar UI to include full-page background images or colors. Use your own images, or purchase from sets of provided themes. For support, see: https://github.com/padster/CalendarThemeExtension/issues **Note** Calendar recently added a dark mode. Support is coming, but for now if wanting to use the extension, it is recommended you use light mode, and instead set a 'dark overlay' in the extension's settings page.