Apply a Kitty color theme. This option takes the file name of a theme in kitty-themes, without the .conf suffix. See https://github.com/kovidgoyal/kitty-themes/tree/master/themes for a list of themes.
Note that if any automatic themes are configured via programs.kitty.autoThemeFiles, Kitty will prefer them based on the OS color scheme and they will override other color and background image settings.