Fonts not working when theme is for only dashboard

Hope someone can explain this to me.

I’m doing modifications to the mushroom theme and one is to change the font.

But I only want it for one dashboard, and it wil not change the font when setting the theme for just that dashboard.

But when I set the theme as global theme, it works just fine. But I don’t want that theme everywhere, just that one dashboard.

So, what is happening?

Sure,I can use card-mod, but it would be far easier to set the font as default.

I’ve tried so many things that I have lost track och it…