class Sass::Tree::Visitors::Convert

def visit_atroot(node)
  if node.query
    "#{tab_str}@at-root #{query_interp_to_src(node.query)}#{yield}"
  elsif node.children.length == 1 && node.children.first.is_a?(Sass::Tree::RuleNode)
    rule = node.children.first
    "#{tab_str}@at-root #{selector_to_src(rule.rule)}#{visit_children(rule)}"
  else
    "#{tab_str}@at-root#{yield}"
  end
end