Nicer Bootstrap is a plugin that changes appearance of Bootstrap's 3 modal window.
It is based on: http://tutorialzine.com/2010/12/better-confirm-box-jquery-css3/
See an example of nicer modal window
See default bootstrap modal window
To get latest version, run command:
git clone https://github.com/Ravaelles/nicer-bootstrap
Nicer Bootstrap uses core Bootstrap modal functionality and it only adds css file that overrides default settings.
Apart from adding the css file the only change needed is to add blue or gray classes to the buttons.
See modal.html file to see an example.