[1] CSS Values and Units Module Level 3 ( (2013-08-23 23:29:23 +09:00 版)) <http://dev.w3.org/csswg/css-values/#common-keywords>

[2] CSS Cascading and Inheritance Level 3 ( (2013-08-23 11:38:39 +09:00 版)) <http://dev.w3.org/csswg/css-cascade/#inherit-initial>