title: Apply CSS when exists one child with specific class
body: <p>I have a dynamic HTML structure and I want to apply a CSS rule only when exists one element that contains one specific class.</p>
  
  <pre><code>&lt;div class="inline-container"&gt;
     &lt;div class="form-element&gt;
        &lt;label class="paragraph"&gt;Some text&lt;/label&gt;   
        &lt;div class="select-wrapper"&gt;
           &lt;select&gt;
              &lt;option value="1"&gt;1&lt;/option&gt;
           &lt;/select&gt;
        &lt;/div&gt;
     &lt;/div&gt;
     &lt;input type="hidden"&gt;
     &lt;input type="hidden"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>When the inputs type are enabled their structure change to the same of "form-element" and of course with the same classes. I only want to apply styles when there are one enabled like in the code. The styles that I want to apply are for the label and for the select. I have tried using only-child or only-of-type but doesn't work fine for that case.</p>
  
  <pre><code>label:only-child {
      padding: 0% 29% 0% 0% !important;
  }
  div:only-child {
      select {
          padding: 0% 10% 0% 59% !important;
      }
  }
  </code></pre>
  
  <p>The HTML cannot be modified only the CSS (.less file)</p>