title: Can't find element in Capybara even though it exists
body: <p>I am writing some Capybara tests, and am failing at what seemed to be quite straight forward search. I have HTML:</p>
  
  <pre><code>&lt;div id="divId"&gt;
  
       &lt;div class="unimportantClass"&gt;
       &lt;/div&gt;
  
       &lt;form id="formId"&gt;
  
          &lt;div&gt;
          &lt;/div&gt;
  
          &lt;h2&gt;Irrelevant text&lt;/h2&gt;
          &lt;p&gt;Equally irrelevant&lt;/p&gt;
  
          &lt;span class="remarkableSpan"&gt;
              &lt;i class="whatever"&gt; &lt;/i&gt;
              Some text
              &lt;input id="targetTag"&gt;
              &lt;/input&gt;
          &lt;/span&gt;
  
       &lt;/form&gt;
  
  &lt;/div&gt;
  </code></pre>
  
  <p>I am trying to confirm existence of "targetTag"</p>
  
  <p>Everything goes well in </p>
  
  <pre><code>expect(page).to have_css('div#divId form#formId span.remarkableSpan')
  </code></pre>
  
  <p>but with </p>
  
  <pre><code>expect(page).to have_css('div#divId form#formId span.remarkableSpan input')
  </code></pre>
  
  <p>or </p>
  
  <pre><code>expect(page).to have_css('div#divId form#formId span.remarkableSpan input#targetTag')
  </code></pre>
  
  <p>it fails to find it. Any ideas what is causing it?</p>