title: How to center input-group inside a div?
body: <p>I want to center the <code>.input-group</code> inside a <code>&lt;div&gt;</code>. When I use the class <code>center-block</code>, the <code>&lt;span&gt;</code> takes the full width and pushes down the input field below it. I want to center them together.</p>
  
  <pre><code> &lt;div class="col-lg-12 col-sm-12 col-md-12 col-xs-12"&gt;
       &lt;div class="input-group input-group-lg inv-amount-block"&gt;
           &lt;span class="input-group-addon" id="inv-rs"&gt;Rs&lt;/span&gt;
           &lt;input type="text" class="form-control" placeholder="Your Amount" aria-describedby="basic-addon1"&gt;
       &lt;/div&gt;
   &lt;/div&gt;
  </code></pre>
  
  <p>I want to center them together like how they are by default.</p>
  
  <p>Here is the <a href="https://jsfiddle.net/68pu5hez/" rel="noreferrer">fiddle</a></p>