This is a bit unfair to file as a bug... but the way CN is used, large blocks of style and other elements are copied between banners. For many reasons, all this stuff should be saved in a template and only the things which are actually changed should be in each banner text.

Looking through meta CN, I think I've identified an obstacle, and addressed with commit https://gerrit.wikimedia.org/r/28913 -- I found that the common elements never (?) included "message fields", possibly because of a quirk in the translation interface, possibly due to misunderstanding.

The message fields serve as named template parameters, basically. We should be able to get a lot more use out of this mechanism before resorting to copy n paste.

Version: unspecified
Severity: major