protected function convertPercentageDimensions(Node $node)
 {
     $parentWidth = $node->getParent() ? $node->getParent()->getWidthWithoutPaddings() : null;
     $parentHeight = $node->getParent() ? $node->getParent()->getHeightWithoutPaddings() : null;
     $node->convertScalarAttribute('width', $parentWidth);
     $node->convertScalarAttribute('height', $parentHeight);
     $node->convertScalarAttribute('max-width', $parentWidth);
     $node->convertScalarAttribute('max-height', $parentHeight);
 }