public static function getCSSClassname($size, $value, $suffix, $min = 1, $max = 12) {

        if ($value < $min || $max < $value) {
            return null;
        }

        $sizes    = ["lg", "md", "sm", "xs"];
        $suffixes = ["offset", "pull", "push", ""];

        if (false === in_array($size, $sizes) || false === in_array($suffix, $suffixes)) {
            return null;
        }
        if ("" !== $suffix) {
            $suffix .= "-";
        }

        return implode("-", ["col", $size, $suffix . $value]);
    }