Change fonts in CSS

[CarolusIII]

Does anybody have experience in selecting different fonts, using CSS in a site created using the dg plugin?
I put an extra line in the custom-style.scss file, because I would like to have certain fonts (h6) in a handwritten style
So, I selected the custom-style scss file in github and added:
h6 {
font-family: Architects Daughter, Au Revoir, Virgil;
}

and then I confirmed the change in Github

But the output is not affected by this.

What is it that I do wrong or do not understand?
How can I know if the selected font is available on the webserver, to begin with?
Anyone?
Thanks.