I use Perkins HTML5+CSS3 framework "He" describes himself as following:
I am a Framework thought to make the life of designers and developers a bit easier. I use the latest Web standards, also known as HTML5 and CSS3. To take more advantage and allow you not to repeat yourself, I am based in LESS.js, which means that you can forget some of the proprietary browser prefixes. Also, I carry a number of preloaded basic styles, mixins, helpers, transparent textures and a @font-face driven icon set. If HTML is your passion, I can help you to make wireframes quickly using the dynamic grid, based in Tyler Tate's 1kb CSS Grid which is already included and can be configured in the perkins.config.less file, as well as many other options.