cache the css as a deck var, don't accidentally send it in sync

anki/deck.py

@@ -1315,6 +1315,7 @@ answerAlign, 0 from cardModels""")])
         (hexifyID(row[0]), row[1]) for row in self.s.all("""
 select id, lastFontColour from cardModels""")])
         self.css = css
+        self.setVar("cssCache", css)
         return css
 
     def copyModel(self, oldModel):

anki/sync.py

@@ -606,6 +606,7 @@ values
         del d['path']
         del d['syncName']
         del d['version']
+        del d['css']
         # these may be deleted before bundling
         if 'models' in d: del d['models']
         if 'currentModel' in d: del d['currentModel']