CSS Tricks: http://css-tricks.com/

Home page: http://lesscss.org/

Home page: http://sass-lang.com/

Faster and easier web development.

Home page: http://getbootstrap.com/

Bootstrap datetimepicker: http://eonasdan.github.io/bootstrap-datetimepicker/

Bootstrap builders: http://pingendo.com/, https://jetstrap.com/

Home page: http://semantic-ui.com/

Home page: http://gumbyframework.com/

Home page: http://foundation.zurb.com/