title: CSS don't work on wicked_pdf
body: <p>I'm using the wicked_pdf and I have a problem. The css don't work. How use correctly?</p>
  
  <p>My code is this:</p>
  
  <p><strong>application.html.erb</strong></p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;WickedPdfExample&lt;/title&gt;
    &lt;%= wicked_pdf_stylesheet_link_tag "bootstrap.min.css" -%&gt;
    &lt;%= wicked_pdf_stylesheet_link_tag "application.css" -%&gt;
    &lt;%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track' =&gt; true %&gt;
    &lt;%= javascript_include_tag 'application', 'data-turbolinks-track' =&gt; true %&gt;
    &lt;%= csrf_meta_tags %&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;div class="container"&gt;
      &lt;%= yield %&gt;
    &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p><strong>layouts/pdf.html.erb</strong></p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;title&gt;PDF&lt;/title&gt;
    &lt;%= wicked_pdf_stylesheet_link_tag "bootstrap" -%&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
    &lt;div class='container'&gt;
      &lt;%= yield %&gt;
    &lt;/div&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p><strong>customers_controller.erb</strong></p>
  
  <pre><code>  def index
      @customers = Customer.all
      respond_to do |format|
        format.html
        format.pdf do
          render :pdf =&gt; 'file_name',
          :layout =&gt; 'layouts/pdf.html.erb'
          :template =&gt; 'customers/index.pdf.erb',
          :show_as_html =&gt; params[:debug].present?
        end
      end
    end
  </code></pre>
  
  <p><strong>index.pdf.erb</strong></p>
  
  <pre><code>&lt;h1&gt;Listing Customers&lt;/h1&gt;
  
  &lt;table class="table table-condensed table-bordered"&gt;
    &lt;thead&gt;
      &lt;tr&gt;
        &lt;th&gt;Name&lt;/th&gt;
        &lt;th&gt;Cpf&lt;/th&gt;
        &lt;th&gt;Occupation&lt;/th&gt;
      &lt;/tr&gt;
    &lt;/thead&gt;
  
    &lt;tbody&gt;
      &lt;% @customers.each do |customer| %&gt;
        &lt;tr&gt;
          &lt;td&gt;&lt;%= customer.name %&gt;&lt;/td&gt;
          &lt;td&gt;&lt;%= customer.cpf %&gt;&lt;/td&gt;
          &lt;td&gt;&lt;%= customer.occupation %&gt;&lt;/td&gt;
        &lt;/tr&gt;
      &lt;% end %&gt;
    &lt;/tbody&gt;
  &lt;/table&gt;
  </code></pre>
  
  <p>And sometimes, get this error:</p>
  
  <p>undefined method `start_with?' for nil:NilClass</p>
  
  <p>What I 'm making wrong?</p>
  
  <p>But, my bootstrap don't charge. I tried ALL!!!</p>