Add the "fade" class to the modal container if you want the modal to fade in on open and fade out on close.
Center the modal vertically and horizontally within the page, with the .modal-dialog-centered class.
Add the .dropleft class next to the dropdown menu to left-align the dropdown. Note that the caret/arrow is added automatically. Also note that we float the dropdown to the right:
Add the .dropright class next to the dropdown menu to right-align the dropdown. Note that the caret/arrows is added automatically: