Bold text doesn’t show up on Chrome for Mac 

Hello! Some people who have Chrome on Mac don’t see bold text in the posts.
For example, on this site which is running the Zuki theme:

Aaptiv 101: Treadmill

The three lines at the bottom – ((Hot & Cold Jog (Beginner) Attack Those Legs (Intermediate) I’m a Diva (Advanced)) – should be in bold, but it doesn’t show up like that on Macs running a Chrome browser. Any idea what’s up? Thanks!