Prevent the page from scrolling when modals are open on iOS

[ludoboludo]

Describe the current behavior

On iOS, when the search is open you can still scroll down the page. iOS isn't working well with our current approach to lock the background when a modal is open. Works on all other devices though.

Describe the expected behavior

When modals are open, you shouldn't be able to scroll the background.

Version information (Dawn, browsers and operating systems)

• Dawn Version: 2.3.0
• Chrome Version 91.0.4472.114
• macOS Version 11.3.1

Possible solution

I had played around with applying a class on the body element to fix it along with some scrolling in case you opened the search from the sticky header further down the page.

Additional context/screenshots
When opening the search on an iOS device, then search something, you will see that you can scroll down the page past the background overlay.

[baldurh]

This is somewhat related to #784

[Stephanie-Chou]

We are closing this issue. This issue was reported 2 years ago on an old version of Dawn. If this is still a high priority issue today, please re open with updated reproduction steps