public function setCssFiles(array $cssFiles)
    {
        $this->cssFiles = ArrayUtils::merge($this->cssFiles, $cssFiles);
        return $this;
    }
public function setCssFiles(array $cssFiles)
    {
        $this->cssFiles = ArrayUtils::merge($this->cssFiles, $cssFiles);
        return $this;
    }
public function setCssFiles ( array $ cssFiles ) { $ this -> cssFiles = ArrayUtils :: merge ( $ this -> cssFiles , $ cssFiles ) ; return $ this ; }
Set custom CSS files

@param array $cssFiles
@return $this
Set custom CSS files