A friend of mine said that to make my website look more professional, I should add a light theme for accessibility. I thought that was a great idea.
But since I have 0 experience with JavaScript, this was quite interesting to implement. I ended up splitting my CSS files into multiple and using JavaScript to switch between them. I also used a cookie so that it will be remembered when you come back to the site.
As my first use of JavaScript, I think it turned out pretty well. I'm happy with the result.