public function addStylesheet($url)
    {
        $url = self::resolveUrl($url);
        if ($url) {
            $this->stylesheets[self::hashResource($url)] = $url;
        }
    }
public function addStylesheet($url)
    {
        $url = self::resolveUrl($url);
        if ($url) {
            $this->stylesheets[self::hashResource($url)] = $url;
        }
    }
public function addStylesheet ( $ url ) { $ url = self :: resolveUrl ( $ url ) ; if ( $ url ) { $ this -> stylesheets [ self :: hashResource ( $ url ) ] = $ url ; } }
Add a CSS stylesheet

@param string $url CSS stylesheet URL
Add a CSS stylesheet