twitter/bootstrap — pull request #7494 by garvincasimir (2013-04-07 01:55:47+00:00)
Title: Added min-height to modal-header for modals with no header text

Modals can be used for alerts which may or may not have a title. When you render a modal with no title the close button appears below the header border. I added a min-height to the modal-header to fix that.