Twitter Bootstrap
Simple and flexible HTML, CSS, and Javascript for popular user interface components and interactions.
Version 3 has come with a tonne of changes including panels, list groups, jubotron, 4 grid sizes, offsets, pushes/pulls and much much more. There have been a few elements removed with the move from version 2 to 3 but the main one is that it’s no longer fixed by default (hooray for responsive).
The new reset can still be found in reset.less, but with many elements removed for brevity and accuracy.
