NVDA screen reader cursor doesn't work correctly when navigating on the card back

Issue Summary

Blind users face difficulty while using the NVDA screen reader cursor to navigate between the card's back and make changes like members, labels, dates, etc. During this process, the NVDA cursor often gets lost between the card's back screen and the board's screen in the background when the card is open. This results in the screen reader reading the board's information rather than reading the information and fields on the card. 

Steps to Reproduce

1. Install NVDA screen reader
2. Go to Trello while NVDA is opened
3. Open your board, and then open a card while the screen reader is active
4. As you navigate through the card's back using the screen reader cursor, you'll notice the cursor doesn't always stay on the card's back when backing out from any of the options from the right-side panel of the card. For example, after adding a member, pressing 'Esc' to back out from the 'Member' popover will result in the screen reader cursor highlighting the board and not the card. 

Expected Results

The NVDA screen reader cursor shouldn't leave the card's back context when the user exits from one of the options on the right-side menu of the card. 

Actual Results

The NVDA screen reader cursor doesn't say on the card's back when leaving one of the field options on the right-side menu of a card. 

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available