3 Disallow invalid hex colors.
11 Longhand hex colors can be either 6 or 8 (with alpha channel) hexadecimal characters. And their shorthand variants are 3 and 4 characters respectively.
17 The following patterns are considered violations:
28 a { color: #12345aa; }
31 The following patterns are *not* considered violations:
46 a { color: #123450aa; }