Bootstrap 3 modal vertical position center

Question

This is a two part question:

1. How can you position the modal vertically in the center when you don\'t know the exact height of the modal?

2. Is

Answer 1

I know it's a bit late, but I am adding a new answer so that it doesn't get lost in the crowd. It's a cross-desktop-mobile-browser solution that works everywhere properly as it should.

It just needs the modal-dialog to be wrapped inside a modal-dialog-wrap class and need to have the following code additions:

.modal-dialog-wrap {
  display: table;
  table-layout: fixed;
  width: 100%;
  height: 100%;
}

.modal-dialog {
  display: table-cell;
  vertical-align: middle;
  text-align: center;
}

.modal-content {
  display: inline-block;
  text-align: left;
}

The dialog starts centered and in cases of large content it simply grows vertically until a scrollbar appears.

Here is a working fiddle for your pleasure!

https://jsfiddle.net/v6u82mvu/1/