modal.css

.modal {
    /*! adjust transition time */
    -webkit-transition: all ease-out !important;
    -moz-transition: all 0.3s ease-out !important;
    -o-transition: all 0.3s ease-out !important;
    transition: all 0.3s ease-out !important;
}
.modal.in .modal-dialog {
    /*! editthis transform to any transform you want */
    -webkit-transform: scale(1, 1) !important;
    -ms-transform: scale(1, 1) !important;
    transform: scale(1, 1) !important;
}
.modal.fade .modal-dialog {
    /*! disable sliding from left/right/top/bottom */
    -webkit-transform: translate(0, 0);
    -ms-transform: translate(0, 0);
    transform: translate(0, 0);
}