extensions/notebook-renderers/src/color.ts/Color/blend
class Color:	blend(c: Color): Color {
		const rgba = c.rgba;

		// Convert to 0..1 opacity
		const thisA = this.rgba.a;
		const colorA = rgba.a;

		const a = thisA + colorA * (1 - thisA);
		if (a < 1e-6) {
			return Color.transparent;
		}

		const r = this.rgba.r * thisA / a + rgba.r * colorA * (1 - thisA) / a;
		const g = this.rgba.g * thisA / a + rgba.g * colorA * (1 - thisA) / a;
		const b = this.rgba.b * thisA / a + rgba.b * colorA * (1 - thisA) / a;

		return new Color(new RGBA(r, g, b, a));
	}