This was a very common pitfall for users. The new logic will reload the
font-size at runtime, but only if the font wasn't manually set by the
user using actions such as `increase_font_size`, `decrease_font_size`,
or `set_font_size`. The `reset_font_size` action will reset our state
to assume the font-size wasn't manually set.
I also updated a comment about `font-family` not reloading at runtime;
this wasn't true even prior to this commit.
67992fde91