I didn't like the slide effect either. To fix this all you have to do is make the the top
attribute the same for both .modal.fade and modal.fade.in. You can take off the top 0.3s ease-out
in the transitions too, but it doesn't hurt to leave it in. I like this approach because the fade in/out works, it just kills the slide.
.modal.fade {
top: 20%;
-webkit-transition: opacity 0.3s linear;
-moz-transition: opacity 0.3s linear;
-o-transition: opacity 0.3s linear;
transition: opacity 0.3s linear;
}
.modal.fade.in {
top: 20%;
}
If you're looking for a bootstrap 3 answer, look here