Blogr landing page with HTML, CSS Grid/ Flex, JavaScript

I really need help with the unsolved: -header gradient background, when adding the second background with hsl, the background pattern disappeared, but with rgba(in this case i use kind of purple, it shows) -JavaScript for toggling navbar menu, burger icon and arrow icon, the menu showed very quickly and disappears right after that. It doesn't stay. -phones image stretches the whole container in art section and I don't know why.

Please tell me what I did wrong! I know there are other minor details that need to be fixed but for now I think about the above. Thanks a lot!