def generate_html
      return false if @css_file.nil? or @html.nil?
      
      css_link = @link_to_css.nil? ? @css_file : @link_to_css
      
      html = WebifyRuby::Html.new(css_link, @html)
      @html_file = html.html_file
    end
def generate_html
      return false if @css_file.nil? or @html.nil?
      
      css_link = @link_to_css.nil? ? @css_file : @link_to_css
      
      html = WebifyRuby::Html.new(css_link, @html)
      @html_file = html.html_file
    end
Internal: Work with Html class and make a HTML5 Doc.
 Create a file under given directory.
 This method should not execute if there is no css file.

 Returns the HTML filepath or nothing.