Forums: Comment field no longer spans width of container

[ndiego]

The comment input field should span the width of the container. I just noticed this today, but this issue was not present during the refresh launch, so perhaps a recent update caused it 🤔

[adamwoodnz]

I noticed it's also overflowing on mobile, causing horizontal scroll.

[adamwoodnz]

I've discovered that there were new styles added for Gutenberg 17.9: Automattic/blocks-everywhere#201, probably before the Forums launch, as the width is set to the old forums width of 620px.

Issue raised, I'll add a hotfix.