Board Thread:General Discussion/@comment-15339176-20150609154245/@comment-5454372-20150609172337

I'd find that debatable actually, according to the two most relevant points I can find in Help:Customization policy:

For the first point, changing the size of the blog title doesn't remove or change the placement or functoinality or any of their main features -- you're not removing any buttons or functions from anywhere. The content below the article title will get moved up or down depending on the size of the article title, but that was always going to happen regardless depending on how long your article title is (e.g. a two-line title would necessarily push down the main article more than a one-line title).

With regards to the second point, it says not "change the position of the article's page title and anything above it" -- neither of which is applicable because you're modifying the page title's size only.

Personally...with what they've currently written, I don't think they've got anything that explicitly stops you from changing font sizes; worst case scenario, they'll simply revert your changes if you're not trying to completely break their ToS usually, so I don't think there should be any harm in changing it first.