Office 365 is trimming characters from our font stack depending on if there are spaces.

If i don't put spaces inbetween the font stack it trims the font family at 40 characters.

font-family:'xxxxxxxxxxxxxxx',Arial,Hel;
font-family:'xxxxxxxxxxx',Arial,Helveti;

If there are spaces it does this.(X is a missing character(s))

font-family:'XxxxxxxXxxxxxxx', Xrial, HelvX;
font-family:'XxxxxxxXxxx', AriaX, HelveticX;

I have narrowed it down to these 2 CSS Styles in one of the media for mobile.

span[class~=mobile-visible] {white-space: pre !important;}
span[class~=mobile-visible]:before {content: '\A' !important; padding-bottom: 40px !important;}

Only removing these two fixes the issue. Commenting them out doesn't work.