title: On input focus change color of label. How?
body: <p>On input <code>focus</code> I want to change the color of the label element. How can I achieve this in less? </p>
  
  <pre><code>.control-label{
        color: @gray-light;
  }
  .controls{
    input,
    textarea{
      background-color:red; 
      &amp;:focus{
        .control-label &amp;{
          color: red;  //HERE
        }
  
      }
  }
  </code></pre>
  
  <p>HTML: </p>
  
  <pre><code>&lt;div class="control-group"&gt;
      &lt;label class="control-label" for="inputEmail"&gt;Firstname&lt;/label&gt;
      &lt;div class="controls"&gt;
          &lt;input type="text" id="inputEmail" placeholder="Firstname"&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>