Function svg 

pub fn svg(lattice: &Lattice, rect: Rect, cut: Cut) -> String

The same picture as an SVG: one <rect> a run of lit sites, on a ground-coloured field, at one unit a site.

Runs rather than one rect a site for the same reason the landing page’s canvas draws runs — a 220x160 lattice is 35,200 sites and perhaps a tenth as many runs.