Using your own themes
You can create custom themes as .conf files and place them in the themes sub-directory of the kitty config directory, typically ~/.config/kitty/themes. The kitten will automatically include them in the list of themes. To modify the built-in themes, name the .conf file Some theme name.conf to override the built-in theme of that name. Here, Some theme name is the actual built-in theme name, not its file name. Note that after making changes, you need to run the kitten and select that theme once for your modifications to take effect.

Or just place the generated colours into:
.config/kitty/kitty.conf
like I do :)

foreground:
background: