modal css

<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
  Launch demo modal
</button>

<!-- Modal -->
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLabel">Modal title</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">×</span>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

	
    <button class="trigger">Click here to trigger the modal!</button>
    <div class="modal">
        <div class="modal-content">
            <span class="close-button">×</span>
            <h1>Hello, I am a modal!</h1>
        </div>
    </div>
	

	
    var modal = document.querySelector(".modal");
    var trigger = document.querySelector(".trigger");
    var closeButton = document.querySelector(".close-button");

    function toggleModal() {
        modal.classList.toggle("show-modal");
    }

    function windowOnClick(event) {
        if (event.target === modal) {
            toggleModal();
        }
    }

    trigger.addEventListener("click", toggleModal);
    closeButton.addEventListener("click", toggleModal);
    window.addEventListener("click", windowOnClick);
	

<!-- Modal HTML embedded directly into document -->
<div id="ex1" class="modal">
  <p>Thanks for clicking. That felt good.</p>
  <a href="#" rel="modal:close">Close</a>
</div>

<!-- Link to open the modal -->
<p><a href="#ex1" rel="modal:open">Open Modal</a></p>