This seems to be caused by a missing closing quote in an attribute in [[pl:Szablon:Infobox mapa lokalizacyjna/core]] (after "margin:3px;"). The opening tag missing the quote is rendered as text.
This is of course trivial to fix in the template itself, but you guys might want to support this - please either make it work or close as INVALID and I'll be happy :)
Version: unspecified
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=51043