Expected behavior

I need that at the moment of defining font-face the same ones appear with the class that I created.

Actual behavior

I defined the fonts in this way, and when I use the black-font class it does not show me the font I defined. I thought it was a problem with the linking of the style.css file inside the assets.php, but no, since I tested the "color" property with the text, and it does work.

Resources (screenshots, code snippets etc.)

.black-font{
    font-family: 'Montserrat-Black' !important; }

@font-face {
    font-family: 'Montserrat-Black', sans-serif;
    src: url('wp-content/themes/mdb-sample-free-wp-theme/assets/fonts/Montserrat-Black.ttf');
  }