syntax: css: differentiate pseudo-classes (now cyan) from comments (blue)

Also, add comments, remove a duplicated ":link", and add ":checked".

syntax/css.nanorc

@@ -3,9 +3,18 @@
 syntax css "\.css$"
 comment "/*|*/"
 
+# First make everything red:
 color brightred     "."
+# Then everything between braces yellow:
 color brightyellow  start="\{" end="\}"
-color brightwhite   start=":" end="([;^\{]|$)"
-color brightblue    ":active|:focus|:hover|:link|:visited|:link|:after|:before"
+# Then everything after a colon white:
+color brightwhite   start=":" end="([;^{]|$)"
+
+# Pseudo-classes:
+color brightcyan   ":(active|checked|focus|hover|link|visited|after|before)\>"
+
+# Comments:
 color brightblue    start="/\*" end="\*/"
+
+# Syntactic characters:
 color green         ";|:|\{|\}"