Responsive code for several boxes within an image

I need help placing five boxes within a larger image. They should float and be responsive. The image is set at 80% of the screen size. The boxes should be centered at the bottom of the screen, and should decrease or increase in size when the screen is resized. It should look good when viewing on a phone.

Below is a screenshot of how it should like, as well as my current code using absolute positioning (which I don’t want to use).