That is from 3 months ago, I find it odd that no apparent work has been done on buttons since then. If this is the final preview, I'm getting the hint that the final release is not off by much -- are they going to put together their efforts on button-designs just in these last few days?
They've always asked that others not host development documentation. Lots of us keep a local copy either for playing around or helping improve them, but you've clearly posted this as a preview of Bootstrap 3 without any permission from Mark.
The "Small device grid" will be the biggest feature for me as bootstrap 2.x gave me some headaches implementing a simple 2 column grid on low resolutions.
Comments like my own are probably the reason @mdo would not like the docs made available to everybody as it spreads potential mis-information and sets expectations that every feature will be in the final product.
I don't know if I goofed up, or chrome went mental, or something else. But I tried to use their bootstrap theme(?) and Chrome started churning through CPU and memory, stopped rendering things, and generally stopped working.
Removed the flatui bootstrap theme, and everything went back to normal.
The main differences - all layout now responsive so no need to include bootstrap-responsive.css and use row-fluid, container-fluid.
All stuff already always fluid now.
Second main point - the framework now mobile ready - that mean a lot of mobile optimisations and widgets for mobile devices.
Foundation was made to support as many screen sizes as possible with minimal fuzz and they're using Sass with Compass. They released version 4 about 5 weeks ago and it is mobile-first. See http://foundation.zurb.com/ .
'Are the buttons going to remain flat?' - no. https://github.com/twitter/bootstrap/pull/6342#issuecomment-...