Flexbox, plenty of grid layout

I really enjoyed the project but a few things gave me issues such as responsiveness. I was able to meet the basic standard for the project but the hero image disappears at a point before it reaches the mobile screen size. If you know any tools that could help out with this, I would really appreciate. What tools, frameworks, or ideas do you think I could use to build this with lesser amount of code. Thank you for your response.