We recently launched a new website (backtothebible.org) designed by an outside company. The site uses Proxima Nova. The font renders great except for a few sizes on PC's. The issue--which is an irregularity of thickness in some characters--is visible at 24px (used by our H3 style) & other sizes close to that. The rendering issue is most noticeable in the lowercase e, s & a.
The web designer has tried everything they know to try, so I'd be thrilled if you had any advice. Thanks!