Grav CMS links in css

I have a problem with adding the custom fonts in Grav CMS. All fonts are added under the folder path: user/themes/bildxwerkstatt/fonts

It works on my computer when I’m adding this code in .css file

@font-face {
font-family: MullerBlack;
src: url(/bildxwerkstatt/user/themes/bildxwerkstatt/fonts/Muller/MullerBlack.otf);}
h1, h2, h3, h4, h5, h6 {
font-family: MullerBlack, sans-serif!important;}

However on the host such path does not work.

As I understood from the Grav documentation the path to font in css should looks like this:


But it does not work in my case. The same problem I have when trying to add background image in css.

Thank you in advance!