add article

Author: davidtheclark

README.md

@@ -18,6 +18,7 @@ Included are resources that articulate key principles and practices. The list is
 
 Newest on top, oldest on bottom. (A note for you outside the US: my dates are month/day/year format.)
 
+- [Side Effects in CSS](http://philipwalton.com/articles/side-effects-in-css/), by Philip Walton (3/3/15)
 - [Used and Abused -- CSS Inheritance and Our Misuse of the Cascade](http://www.phase2technology.com/blog/used-and-abused-css-inheritance-and-our-misuse-of-the-cascade/?utm_source=CSS-Weekly&utm_campaign=Issue-127&utm_medium=RSS), by Micah Godbolt (8/25/14)
 - [Enduring CSS: writing style sheets for rapidly changing, long-lived projects](http://benfrain.com/enduring-css-writing-style-sheets-rapidly-changing-long-lived-projects), by Ben Frain (8/7/14)
 - [Challenging CSS Best Practices](http://www.smashingmagazine.com/2013/10/21/challenging-css-best-practices-atomic-approach/) -- suggesting a unique approach (all utility classes) the author calls Atomic CSS -- by Thierry Koblentz (10/21/13)