As @J_Canan rightly pointed out, using the breakpoints helps define the design based on the device being used to view your site.
Creating a site for every single screen size is impossible though, so making things move depending on the screen size, whatever that may be, is the best thing to do.
When you use pixel sizes as you have done in your project, then you are telling the div block to be 1220px, no matter what. Webflow is great because it listens to the commands you give, and it won’t budge from 1220px.
So a great trick, is to set a maximum width of 1220px, and width of 100%. This tells Webflow that on a huge screen, that div block will be maximum 1220px, but if the screen is smaller, then it will stick to 100% of whatever screen it’s on.
This can sound a bit confusing, so i did a video to try and help and as it uses your design it will hopefully be clearer. It’s around 7minutes, and sorry in advance if I’m waffling on a bit!
You can also check out the university videos on responsive design too: https://university.webflow.com/topic/responsive-design
If you have any questions, please feel free to reach out here anytime