public function build(array $classes, string $size = ''): array
    {
        $sizeSuffix = $size ? '-' . $size : $size;

        if ($this->width === 'auto') {
            $classes[] = 'col' . $sizeSuffix . '-auto';
        } elseif ($this->width === null || $this->width > 0) {
            $widthSuffix = ($this->width > 0) ? '-' . $this->width : '';
            $classes[]   = 'col' . $sizeSuffix . $widthSuffix;
        } elseif ($size) {
            $classes[] = 'd-' . $size . '-none';
        } else {
            $classes[] = 'd-none';
        }

        $this->buildAlign($classes, $sizeSuffix);
        $this->buildJustify($classes, $sizeSuffix);
        $this->buildOrder($classes, $sizeSuffix);
        $this->buildOffset($classes, $sizeSuffix);

        if ($this->cssClasses) {
            $classes = array_merge($classes, $this->cssClasses);
        }

        return array_unique($classes);
    }