% in fmt.Fprintf must be %%.inline-size: 100%% in the format string.
%g for coordinates — clean float output (70, not 70.000000).
Raw string literals (backticks) for SVG fragments. Keep them balanced —
go build ./... is the checker; this is compiled Go, so compile early and often.
Don't hand-color anything. If you typed #, rgb, oklch(, or a color name into
a chart, stop — it's wrong. Color comes from --fg + --hue-shift only.
--fg goes on the element/group, currentColor on the paint. Setting fill="--fg"
or a bare --fg with no currentColor paint does nothing.