Lepton v5.0 – Firefox's 100 options and unopinionated custom theme

- Option

As a first anniversary update, an option system is introduced.

Everything can be configured with 100+ options and changes to a unopinionated theme.

- Customize

To enhance customization, we changed the folder structure and updated the installation script.

If there are any changes: Run `git stash` and `git stash pop` before and after `git pull`. If there are `user-overrides.js`, `userChrome-overrides.css`, and `userContent-overrides.css` files, proceed with override

- Developement

The Pure CSS file has been changed to SCSS. Therefore, it becomes more structured, and the compatibility response has become easier.

Developer documents have been added to facilitate development, and discussions have been activated.