Fix *-child syntax highlighting

Author: jasonwilliams

syntaxes/css.styled.json

@@ -1100,9 +1100,13 @@
               "include": "#interpolation"
             },
             {
-              "match": "\\d+",
+              "match": "(?i)[+-]?(\\d+n?|n)(\\s*[+-]\\s*\\d+)?",
               "name": "constant.numeric.css"
             },
+            {
+              "match": "(?i)even|odd",
+              "name": "support.constant.parity.css"
+            },
             {
               "match": "(?<=\\d)n\\b|\\b(n|even|odd)\\b",
               "name": "constant.other.scss"