Answers for "vertically center modal"

css center modal vertically

.yourElement{
  position: relative;
  top: 50%;
  transform: translateY(-50%);
}

vertically center a modal

<!-- Vertically centered modal -->
<div class="modal-dialog modal-dialog-centered">
  ...
</div>

<!-- Vertically centered scrollable modal -->
<div class="modal-dialog modal-dialog-centered modal-dialog-scrollable">
  ...
</div>