Traditional web design has been about crafting a series of explicit declarations with inline, embedded and linked styles. Weaving through the different layers of stylesheets, these CSS rules come together to form a final presentational ruleset. Undoing those rules or forming exceptions to them has been a difficult task, often relegated to “napalm the forest” CSS resets or the tedious reversal of property values. Until very recently, it’s been impossible to easily create a rule that says, “apply these values to everything but this element.”