Also, browsers seem to render svg circular arcs using bezier curves. At high zoom levels there can be quite a discrepancy between the actual curve (drawn using lots of straight line segments, say) and what the browser renders for a circle.
Do they? I thought this is more issue on the source code side, rather than implementation: this is actually my pet-peeves, that most SVG *authoring tools* never output circular arcs and always use cubic béziers approximations instead. So we nearly ever see real circles or their segments, even though authors use them in their designs all the time.
It was a few years ago and I'm unable to reproduce it. Circles and circle approximations from straight lines seem to coincide exactly in Firefox and Edge now.
I was generating diagrams using my own code so I'm positive they were circular arcs. Tangents weren't tangent and it took me a while to realise that the problem was the browser rendering something that wasn't quite a circle. I assumed it was a bezier approximation but I didn't verify that. Whatever it was it seems to be fixed.
