如何在.NET中没有jQuery的情况下让Bootstrap模式停留在屏幕上？

<link rel="stylesheet" href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/5.1.3/css/bootstrap.min.css">
<script src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/5.1.3/js/bootstrap.min.js"></script>

<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h4 class="modal-title" id="myModalLabel">Modal Header</h4>
        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
      </div>
      <div class="modal-body">
        <p>Modal Body</p>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div><!-- /.modal-content -->
  </div><!-- /.modal-dialog -->
</div><!-- /.modal -->

document.getElementById("myModal").style.display = "block";