func (s *selectable) First(selector string) *Selection {
	return newSelection(s.session, s.selectors.Append(target.CSS, selector).At(0))
}
func (s *selectable) First(selector string) *Selection {
	return newSelection(s.session, s.selectors.Append(target.CSS, selector).At(0))
}
// First finds the first element by CSS selector.