A band of split light in the dark behind a section, blue at one end and amber at the other with a bright core: Prism's light at a chosen place, a hero, the plan you sell or the closing call to action. Drawn live by default: it turns slowly in depth like a ribbon and its spectrum flows, more while the page moves; it moves at its own depth as its section passes, and a pulse of light runs along it while the page scrolls. Without WebGL, on a light page or under reduced motion it is the painted band. Draws only on screen. (Beamline complete system)