I can't to hightlight Rouge

Question

rouge_helper.rb:

module RougeHelper
require 'rouge'

  def rouge(text, language)
    formatter = Rouge::Formatters::HTML.new
    lexer = Rouge::Lexer.find(language)
    formatter.format(lexer.lex(text))
  end

end

app/assets/stylesheets/rouge.css.erb:

 <%= Rouge::Themes::Base16.mode(:light).render(scope: '.highlight') %>

index.html.erb:

<% @articles. each do |article|%>
<p><%= article.title%></p>
<p><%= raw rouge article.text, 'ruby'%></p>
<% end >

view page source:

<p>test </p>
<p>&lt;span class=&quot;k&quot;&gt;def&lt;/span&gt; &lt;span class=&quot;nf&quot;&gt;test&lt;/span&gt;
 &lt;span class=&quot;nb&quot;&gt;puts&lt;/span&gt; &lt;span class=&quot;s1&quot;&gt;&#39;Hello&#39;&lt;/span&gt;
&lt;span class=&quot;k&quot;&gt;end&lt;/span&gt;</p>