Styling changes not showing

I am using Divi 4.0.6 and WordPress 5.3 (current latest versions), but am having problems get the styling settings to take effect.

Some things work, but two things which don’t are
– the borders on the input fields (I want to remove them or set them to the same as the background but they stay resolutely grey!)
– any styling of the Submit button … just ignores any custom styling I set.

Any ideas why this might be?

Thanks