To override this (or any other) theme in your personal config file, please follow the guide in the color theme documentation. This is handy for small tweaks to the theme without having to fork and maintain your own theme.
Run npm run build to update the theme. You can also run npm run start instead to automatically rebuild the theme while making changes and no reloading should be necessary.
Once you're happy, commit your changes and open a PR.
Scripts
Script
Description
npm run build
Builds the theme .json files in ./themes directory