This website and its sample code creates a template of sorts, absent of design or layout, that will help you avoid some of the major rendering problems with the most common email clients out there — Gmail, Outlook, Yahoo Mail, etc.

• We shifted to using normalize.css instead of the bulldozer reset.css and base approach. This ends up being smaller, faster, and easier to develop with.
• IE6 users will now be prompted to install Chrome Frame by default. Its time. :)
• The build script continues to get massively improved: any css @imports get inlined into your file before it gets concatenated with other files and minified together, the application caches manifest is generated automatically for you if you want to take your app offline, also this whole build process is way faster now.
• Build script also has optional tasks for CSSLint, JSHint, splitting your CSS into modules, and more customizability.
• Added respond.js to allow true responsive development; use media queries with full cross-browser support now!
• PNGFix, Handheld.css removed along with lots of other smart removals. The full h5bp payload is now smaller and faster than ever.