in sim/visuals/board.ts [201:212]
private addDefs(el: SVGElement) {
const defs = svg.child(el, "defs", {});
let neopixelglow = svg.child(defs, "filter", { id: "neopixelglow", x: "-200%", y: "-200%", width: "400%", height: "400%" });
svg.child(neopixelglow, "feGaussianBlur", { stdDeviation: "4.3", result: "coloredBlur" });
let neopixelmerge = svg.child(neopixelglow, "feMerge", {});
svg.child(neopixelmerge, "feMergeNode", { in: "coloredBlur" })
svg.child(neopixelmerge, "feMergeNode", { in: "SourceGraphic" })
const style = svg.child(el, "style", {});
style.textContent = STYLE;
}