Bootstrap's RWD breakpoints
/* http://twitter.github.com/bootstrap/scaffolding.html#responsive */
/* Landscape phones and down */
@media (max-width: 480px) { ... }
/* Landscape phone to portrait tablet */
@media (max-width: 768px) { ... }
/* Portrait tablet to landscape and desktop */
@media (min-width: 768px) and (max-width: 940px) { ... }
/* Default: 940px and up */
/* Large desktop */
@media (min-width: 1210px) { ... }