[Fixed in 6.4] Buy Extra Delve attempts button hidden with many resolutions (Choose difficulty screen)

Platform, device version and operating system:
Steam - Windows 10 Home

Screenshot or image:
1280 X 1024 Gems Of War Delve 1280X1024 Extra delve button cut off - Album on Imgur
1600 X 1024 Gems of War - 1600X1024, 1680X1050 Delve - Extra Delve button - Album on Imgur
and 1680 X 1050

What you were expecting to happen, and what actually happened:
If you have a more squarish resolution, (eg 4:3 vs 8:5) the green purchase delve buttons is cutoff or missing.
Expected: This button is part of the element that is right aligned, so that it is always visible at the top right

How often does this happen? When did it begin happening?
Probably started happening when button was added.

Steps to make it happen again
Obvious prereq: You need access to a delve.
View a delve where you do not have an active delve. Click the Delve button to access the difficulty choice screen. Examine top right.
Resize the window, noting when the green button disappears. If you want to use a default resolution before doing this, you can use 800X640

It’s the same on mobile. I have to use my phone to be able to properly access that button.

Button should be in another spot to prevent this.