public function addClass($class) {
		$class = trim($class);
		
		if (strpos($class, ' ') !== false) {
			$this->addClasses(explode(' ', $class));
			return $this;
		}
		
		$this->_classes[$class] = $class;
		$this->_tagCached       = null;
		
		return $this;
	}