in src/theme.js [71:81]
  size(key: Size) {
    const size = SIZES[key];
    if (size.min == null) {
      return media.lessThan(key);
    } else if (size.max == null) {
      return media.greaterThan(key);
    } else {
      return media.between(key, key);
    }
  },