Css inliner using Nokogiri and css_parser

inline_css_helper.rb

require 'nokogiri'
require 'css_parser'

module InlineCSSHelper
  
  include CssParser
  # Takes a string of HTML and inlines any css blocks in it.
  def inline_css(message)
    css_parser = CssParser::Parser.new
    doc = Nokogiri::HTML(message)
    # Collect the style and remove from the html tree
    doc.css('style').each_with_index do |style, i|
      css_parser.add_block!(style.content)
      style.remove
    end
    css_parser.each_selector do |selector, declaration|
      # Each selector
      doc.css(selector).each do |node|
        # On to each element, let existing styles be at the top of the cascade
        node['style'] = node['style'].nil? ? 
        declaration : CssParser.merge(RuleSet.new(nil, declaration), RuleSet.new(nil, node['style'])).declarations_to_s
      end
    end
    doc
  end
  
end