title: Bootstrap3 Icons how align icon on center in div?
body: <p>Code:</p>
  
  <pre><code>&lt;div class="input"&gt;
  &lt;div class="icon glyphicon glyphicon-user"&gt;&amp;nbsp;&lt;/div&gt;
  &lt;input type="text" name="username" maxlength="20" placeholder="Login"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>In result we have:</p>
  
  <p><img src="https://i.stack.imgur.com/NWLaI.jpg" alt="enter image description here"></p>
  
  <p>Tell me please how make <strong>in my code</strong> that icon will be in center white block?</p>