Invisible font display issue

Question

I seem to be getting a problem where my fonts aren't displaying properly until the dom is manipulated somehow after the initial load. The page is https://www.gemalley.com/ - fonts appear blank or invisible in Safari/Chrome until for instance the menu icon is clicked, or the first banner animation is triggered. They also don't work on firefox or ie at all for me.

Haven't a clue why this is happening so would much appreciate it if someone could point me in the right direction.

Thanks