Dont complain about panose-1

src/calibre/ebooks/oeb/polish/check/parsing.py

@@ -192,6 +192,8 @@ class ErrorHandler(object):
         if msg and line is not None:
             # Ignore error messages with no line numbers as these are usually
             # summary messages for an underlying error with a line number
+            if 'panose-1' in msg and 'unknown property name' in msg.lower():
+                return  # panose-1 is allowed in CSS 2.1 and is generated by calibre
             self.errors.append(CSSError(level, msg, self.name, line, col))
 
     def error(self, *args):