intro section with dropdown navigation + dark mode

WOW I added a little extra (dark mode and light mode) I used CSS only for all, as I have not started my JS journey

I had though time with the css selectors, seeing that no JS was involved

One question

when building a responsive bar for both web and mobile, with the aim of the mobile nav to be a slide at the right side of the screen, do you create 2 html structure for both web and mobile, or you use one for both

Actually, i used one, but the tweaking was too much, such that I had to change from flex to fixed. I felt it was over done

Thank you for your suggestion