I have a SVG file with fill="none" specified in the root <svg ...> element. With
this setting, polygons are filled black by the WikieMedia engine. When I repeat
the attribute in the containing <g ...> group, the polygon is correctly just
stroked and not filled. The same is true for stroke width; it is inherited from
parent <g ...> elements but not from the root <svg ...> element.
On the URL which I supplied, the first version I uploaded is rendered black, the
second one rendered transparent. In the third version I moved the width
specification as well, which fixed that problem as well.