Browser extension manager, scss, vanilla JS

What are you most proud of, and what would you do differently next time?

If I had to do it all from the start I would invest more time in brainstorming mode.

What challenges did you encounter, and how did you overcome them?

Main challenge for me was implementing JS logic and creating dark theme.

What specific areas of your project would you like help with?

I'd like help with JS; is there better way to do it with less code and more DRY, are there any flaws in my logic and possible improvements? Also, there is a lot of repetition in SCSS especially with implementing of theme switching; like with JS, is there anything I can do to trim the amount of code and reduce repetition.