title: Detect user agent jekyll
body: <p>I would like to render different html for desktop and mobile on jekyll. I need something like:</p>
  
  
  
  <pre><code>{% if is_mobile %}
      &lt;!-- mobile html --&gt;
  {% else %}
      &lt;!-- desktop html --&gt;
  (% endif %}
  </code></pre>
  
  <p>Obviously I could just use javascript in the browser to determine this but I don't want to render the extra html for mobiles.</p>
  
  <p>Maybe I could create a jekyll plugin and register the liquid tag but how can I get access to the user agent? Is there anyway I can get access to HTTP request parameters?</p>