Reply where modal is out of screen on mobile

[Don]

Hello,

It seems to this commit push the reply where modal to out of screen on mobile devices.

https://github.com/discourse/discourse/commit/9b55c42eee454865ca550c7a16249aaca8bb76ac

Thanks

[zogstrip]

@Don can you still reproduce?

[Don]

It looks perfect now. Thank you!