Font CSS

Hi all,
So to start; I’m a complexe no brainer in building websites so please help me out 😉
I’ve installed hummingbird today to fix the terrible speeding of my website, especially on mobile.

I’ve been trying to fix this thing with fonts, but somehow my CSS doesn’t recognize it. I use the customizer from WP to add additional CSS.

My run test said:
Diagnostics:
Ensure text remains visible during webfont load. Your page is not using font-display rule when loading the following web fonts.

For fonts hosted locally, add the font-display property to the @font-face CSS rule as shown below:

@font-face{
font-family: ‘myWebFont’;
font-display: swap;
src: url(‘myfont.woff2’) format(‘woff2’);
}

So that’s what i did, but the @font-face stays red and even after applying and running a new test, I still get this problem.

How to fix ?

The page I need help with: [log in to see the link]