Font family different on Safari mobile and desktop

[CloYou]

Hi there, 

I recently changed our H1 and H2 font family to Playfair Display - it's working well on Chrome however on mobile (Safari) it's showing what looks like Times New Roman. This is only happening with our Collection pages as these are built using Shopify's Debut template - our other pages are built with Shogun and there are no issues there. 

https://www.albaray.co.uk/collections/view-all

I've had a look into the code but can't seem to find where to fix this issue. 

Any help would be appreciated!