src/Context/RawPageContext.php
public function findByCss($selector)
    {
        return $this->getWorkingElement()
            ->find(empty($this->getDrupalParameter('region_map')[$selector]) ? 'css' : 'region', $selector);
    }
public function findByCss($selector)
    {
        return $this->getWorkingElement()
            ->find(empty($this->getDrupalParameter('region_map')[$selector]) ? 'css' : 'region', $selector);
    }
@param string $selector

@return NodeElement