Undefined variable

All of a sudden, I feel to drop a few lines on this topic when it came to my mind. It may be an outdated topic and most people already aware of this but I believed that thought sharing  is always a good thing to do. Recently, ...

http://www.smashingmagazine.com/2008/02/21/powerful-css-techniques-for-effective-coding/

http://www.alistapart.com/articles/neveruseawarning

http://www.alistapart.com/articles/frameworksfordesigners