def to_css
      css = ''
      css << resolved_modifier
      css << ' ' unless resolved_modifier.empty?
      css << resolved_type
      css << ' and ' unless resolved_type.empty? || expressions.empty?
      css << expressions.map do |e|
        # It's possible for there to be script nodes in Expressions even when
        # we're converting to CSS in the case where we parsed the document as
        # CSS originally (as in css_test.rb).
        e.map {|c| c.is_a?(Sass::Script::Tree::Node) ? c.to_sass : c.to_s}.join
      end.join(' and ')
      css
    end
def to_css
      css = ''
      css << resolved_modifier
      css << ' ' unless resolved_modifier.empty?
      css << resolved_type
      css << ' and ' unless resolved_type.empty? || expressions.empty?
      css << expressions.map do |e|
        # It's possible for there to be script nodes in Expressions even when
        # we're converting to CSS in the case where we parsed the document as
        # CSS originally (as in css_test.rb).
        e.map {|c| c.is_a?(Sass::Script::Tree::Node) ? c.to_sass : c.to_s}.join
      end.join(' and ')
      css
    end
Returns the CSS for the media query.

 @return [String]