title: Bootstrap 3 to 4 Migration in File Upload button and Input size issue
body: <p>I have been using the below Snippet for a while now. But when I try to move the same code to Bootstrap 4, The Button size and Input Box size are not aligning.</p>
  <h3>Bootstrap 3 File Upload Snippet</h3>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.min.css"&gt;
  &lt;div class="col-md-10"&gt;
      &lt;div class="input-group"&gt;
          &lt;label class="input-group-btn"&gt;
              &lt;span class="btn btn-primary"&gt;
                  Choose File &lt;input type="file" id="pdf-file" name="pdf_file" style="display: none;"&gt;
              &lt;/span&gt;
          &lt;/label&gt;
          &lt;input type="text" class="form-control" id="pdf-name" placeholder="Select the PDF File" readonly&gt;
      &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  <h3>Bootstrap 4 File Upload Snippet</h3>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0/css/bootstrap.min.css"&gt;
  &lt;div class="col-10"&gt;
      &lt;div class="input-group"&gt;
          &lt;label class="input-group-btn"&gt;
              &lt;span class="btn btn-primary"&gt;
                  Choose File &lt;input type="file" id="pdf-file" name="pdf_file" style="display: none;"&gt;
              &lt;/span&gt;
          &lt;/label&gt;
          &lt;input type="text" class="form-control" id="pdf-name" placeholder="Select the PDF File" readonly&gt;
      &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  <h3>Please help me migrate the above code to Bootstrap 4.</h3>