Sleek, intuitive, and powerful mobile first front-end framework for faster and easier web development.
#css
OverAPI.com
Cheat sheets/references for all sorts of programming languages.
Brackets
Open-source code editor, built with the web for the web.
All you need to know about CSS Transitions
All you need to know about CSS Transitions
Nice primer on CSS3 animations from Alex.
SpritePad
Online tool for creating and editing CSS spritemaps. Upload images, compile map, get auto-CSS.
Normalize.css
Normalize.css makes browsers render all elements more consistently and in line with modern standards. It precisely targets only the styles that need normalizing.
ProCSSor
Powerful CSS prettifier. Lots of nice rules to be able to generate CSS according to our preferred format.
How to lose weight (in the browser)
How to lose weight (in the browser)
What if we got together a bunch of experts who work on large sites to create a definitive front-end performance guide?
HTML Email Design Guidelines
From Campaign Monitor. HTML Emails are horrible, as evidenced by all the horrible things going on in this excellent guide.