code: function filterFont({ atRules, values }) {
    values = uniqs(values);
    atRules.forEach((r) => {
      const families = r.nodes.filter(({ prop }) => prop === 'font-family');
  
      // Discard the @font-face if it has no font-family
      if (!families.length) {
        return r.remove();
      }
  
      families.forEach((family) => {
        if (!hasFont(family.value.toLowerCase(), values)) {
          r.remove();
        }
      });
    });
  }
docs: fonts have slightly different logic