原文：https://www.w3.org/TR/CSS2/cascade.html#computed-value
Some examples:
* {} /* a=0 b=0 c=0 d=0 -> specificity = 0,0,0,0 */ li {} /* a=0 b=0 c=0 d=1 -> specificity = 0,0,0,1 */ li:first-line {} /* a=0 b=0 c=0 d=2 -> specificity = 0,0,0,2 */ ul li {} /* a=0 b=0 c=0 d=2 -> specificity = 0,0,0,2 */ ul ol+li {} /* a=0 b=0 c=0 d=3 -> specificity = 0,0,0,3 */ h1 + *[rel=up]{} /* a=0 b=0 c=1 d=1 -> specificity = 0,0,1,1 */ ul ol li.red {} /* a=0 b=0 c=1 d=3 -> specificity = 0,0,1,3 */ li.red.level {} /* a=0 b=0 c=2 d=1 -> specificity = 0,0,2,1 */ #x34y {} /* a=0 b=1 c=0 d=0 -> specificity = 0,1,0,0 */ /* a=1 b=0 c=0 d=0 -> specificity = 1,0,0,0 */<HEAD><STYLE type="text/css"> #x97z { color: red }</STYLE></HEAD><BODY><P ID=x97z style="color: green"></BODY>In the above example, the color of the P element would be green. The declaration in the "style" attribute will override the one in the STYLE element because of cascading rule 3, since it has a higher specificity.
