Responsive Page Using Simple Html + Css + Flex

Wow, this one was kinda difficult to organize. A lot of divs for elements that would be misaligned on purpose and that's the first time I've been able to get desired proportions/alignment with all the elements. (Had to use a lot of margin and padding for that, though.) Tried and made everything smooth as possible when resizing the window using Flex as much as possible. Couldn't figure out if there's a way to use less padding/margin for some minor adjustments. Anyway, I'm really proud of the result. Definitely my best challenge submission! As always, any feedback is welcome, thanks in advance!