SVGs made by Cairo in Markdown context interact with each other

[cormullion]

I'm reporting this issue here, although it was originally posted here.

https://user-images.githubusercontent.com/52289/178143133-28ebe9d7-b404-462e-ae5d-05a5b3cf5ab9.mov

The user is using Markdown to include SVG images. Unfortunately, the glyph-ids in the SVG images "leak", and interact with each other in unfortunate ways.

It's a well-known problem with SVGs made by Cairo (https://github.com/JuliaPlots/Makie.jl/issues/952#issuecomment-842413678). It's not usually a problem in Pluto (if you make SVGs in the normal way), but the use of Markdown complicates it (for me, anyway).