Allow uppercase hex chararcters in CSS colour check

Author: hugovk

html5lib/filters/sanitizer.py

@@ -855,7 +855,7 @@ def sanitize_css(self, style):
                                                 'padding']:
                 for keyword in value.split():
                     if keyword not in self.allowed_css_keywords and \
-                            not re.match(r"^(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$", keyword):  # noqa
+                            not re.match(r"^(#[0-9a-fA-F]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$", keyword):  # noqa
                         break
                 else:
                     clean.append(prop + ': ' + value + ';')