User blog comment:Rupert Giles/Layout Changes: Breakpoints and Typography/@comment-126761-20150520135725

Picking this out from a previous post, as it is disappearing down the page: there is a known issue that is causing walls and forums (and some blog-related pages) to display especially oversized fonts, particularly on the Desktop XL format - this was not intentional. The font size tweaks seen on article pages are the intended (and significantly smaller) change. We'll try and get fixes live for this soon.

Edit: and just to quickly add to this - we're also working on the issue preventing users on smartphones from being able to zoom out, after switching to the full site skin.