public function addCss($path,$priority=5,$group='head',$slot=null) {
		$this->add($path,'css',$group,$priority,$slot);
	}
public function addCss($path,$priority=5,$group='head',$slot=null) {
		$this->add($path,'css',$group,$priority,$slot);
	}
public function addCss ( $ path , $ priority = 5 , $ group = 'head' , $ slot = null ) { $ this -> add ( $ path , 'css' , $ group , $ priority , $ slot ) ; }
add a css asset
@param string $path
@param int $priority
@param string $group
@param null $slot
add a css asset