Glad to hear adjusting things a bit were able to help! I just took a peek and it appears that your changes helped out with the presentation on the larger screens—although it’s weird that the two browsers were interpreting the breakpoints a bit different in the first place 
I took a peek in DevTools to see if I noticed any overlap on iPhone 6, and while the interpreted viewport size didn’t show any overlap, I’d imagine sizes differ on actual devices and the addition of the address bar would have shortened the height and caused text to be unreadable:
The reason you’re running into issues is because the photo is always stuck to the bottom and both the height of the section and the photo are set in vh
units—meaning if the height of the device is under ~650px then there will be overlap on the hero copy:
Instead, I’d recommend having the photo within it using %
units. Since your parent container has a height applied, using %
here means it will only take up a percentage of it’s container—rather than the entire viewport height.
Using the same size from the example above, changing the height of the image from 60vh
to 60%
fixes the problem:
Hopefully that helps 