How can I vertically centralize a Bootstrap V4 modal with CSS? [duplicate]

Question

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• How to vertically align Bootstrap v4 modal dialogs 8 answers

How can I centralize a Bootstrap V4 modal with CSS?

Answer 1

You can vertical center the modal by overriding the position of the .modal-dialog like this..

.modal.show .modal-dialog {
    -webkit-transform: translate(0,-50%);
    -o-transform: translate(0,-50%);
    transform: translate(0,-50%);
    top: 50%;
    margin: 0 auto;
}

http://www.codeply.com/go/14Ki1kyTgo

Update 2018

As of Bootstrap 4 Beta 3, there is a new modal-dialog-centered class that can be used instead of the custom method described above.

https://www.codeply.com/go/lpOtIFoN6E (Beta 3)

Answer 2

Using Flexbox its really easy to add vertical align bootstrap 4 modal popup. Here's the CSS Code.

See Woking Demo

SASS

.modal-open .modal.modal-center {
    display: flex!important;
    align-items: center!important;
    .modal-dialog {
        flex-grow: 1;
    }
}

Compiled CSS

.modal-open .modal.modal-center {
  display: -webkit-box !important;
  display: -ms-flexbox !important;
  display: flex !important;
  -webkit-box-align: center !important;
      -ms-flex-align: center !important;
          align-items: center !important;
}
.modal-open .modal.modal-center .modal-dialog {
  -webkit-box-flex: 1;
      -ms-flex-positive: 1;
          flex-grow: 1;
}

See Woking Demo