Why does the font itself change in the navigation of a wordpress site?

Question

css

Good day. The menu on the site uses the Roboto font. But it is displayed only on the main page, and on the rest it changes to Arial. Tell me how can this be fixed? Site on Wordpress. https://eco-obrabotka.ru/
That's right (on the main page):

That's not right:

Answer 1

So vice versa. In your examples, Roboto is at the bottom, and Arial is at the top, and by the way, the phone number is another third font.
According to your link, I have Roboto everywhere in FF and Chrome.
upd1.
in FF, for some reason, the fonts really move out on the main page, as shown in your top picture.