You’re not the first person to mention this—I’m sorry. Does font-weight: 400; on the body copy help? (Sorry to make you do the legwork but for me the type is perfectly legible as it is, so I need someone else to verify.)
For reference, I'm on Chrome, Win 10. The above image is at 125% zoom in Chrome, magnified 16x to see the pixels. I don't mind testing though, this helps me a lot - now I know what property to change or suggest if I see another site that does this to me.
The best thing monitor manufacturers even did was see 4k monitors to designers.