Hi Antoine,
This looks really broken for me I'm afraid. I think it's because you're using explicit sized margins on the .container. Instead, if you just used a max-width on that, gave it a small bit of padding, and had the margins set to auto on left and right it would be much more responsive.
Then all you'd need to do is set the flex-direction on the bottom section to column in a media query for mobile.
If you ever want to learn CSS grid, this is a great beginner challenge for it, so maybe return to this again when you look at that.
Keep going with your coding journey :) (And please upvote if you found this comment helpful)