Segregate theme config

[Naapperas]

We should not have the configuration for the Website's theme situated on the Tailwind's configuration file.

In my opinion, we should have:

• The color palette on a dedicated file, where we define all the colors that are going to be used throughout the website. As a bonus, we could think of some "standard" way of using these colors so that future developers only need to change some values and everything still works.
• Adittional styling should be on a separate file (that must respect Tailwind's configuration format) that is imported and used on the main config file.

This way, we ensure that any styling that is not permanent can be modified and the website adapts to it.