I will keep updating this list as I find more tools
here you can generate css for columns , transisitions etc
http://css-tricks.com/almanac/
great list of often forgotten css selectors and properties
http://blog.gfk.com/2014/05/2014-mobile-ux-design-trends-embracing-minimal/
This one isn’t a css tool but a worthwhile article on mobile design which css is a big part of