Used CSS custom properties (:root {})

Of course, I was lost when I was left alone to be able to code that! I helped myself with YouTube, but we all do, right? At least we are beginners😊😊 So, what did I find difficult? ehmm, to start? I was unsure of the idea of how and where to link my CSS! Ideas about best practices? Well, it's in the word! Practice, practice, and once again, practice!