CSS2
Cascading Style Sheets, level 2
1998-01-28: 草案
https://www.w3.org/TR/1998/WD-css2-19980128/
1998-03-24: 勧告案
https://www.w3.org/TR/1998/PR-CSS2-19980324/
1998-05-12: 勧告
https://www.w3.org/TR/1998/REC-CSS2-19980512/
2008-04-11: 改訂
https://www.w3.org/TR/2008/REC-CSS2-20080411/