Font display, chrome and firefox, why is there a difference?

Question

css

Hello, for a long time I began to use the Open+Sans font
fonts.googleapis.com/css?family=Open+Sans:300italic ,400italic,600italic,700italic,800italic,400,300,600,700,800&subset=cyrillic,cyrillic-ext
If you make the font bolder, let's say 600-800 , in mozilla it looks good, in chrome it is not clear, here are comparisons, what to do with it? maybe there is a solution.
I have attached a screenshot of the comparison.

Answer 1

fonts4web.ru/opensans.html
Use a separate Open Sans bold instead of font-weight