Is it possible to import/use a custom web font? I can’t seem to get it to work, would like to make sure I’m not banging my head against a brick wall.
I don’t think there’s a straightforward way to do it.
Most web fonts support the CSS @import approach, but the browsers are strict about requiring the @import statement to be the first statement in a style block.
In the case of SharpTools Custom CSS, the custom CSS is the last thing that gets appended to the style block to make sure any of the ‘base’ styles defined in a Theme can be overridden. So that means Custom CSS won’t work in this case. 
If you’re using Fully Kiosk Browser, you might be able to use the ‘Inject JavaScript’ feature to accomplish it, but it’s certainly and advanced use-case.
The concept is briefly documented in the '▸Alternative method using Fully Kiosk Browser's Inject JavaScript Feature' collapsed section of this post which you can tap to expand.