Each cell runs a local PID controller regulating its active-neighbour count toward a target. Switch Domain / mechanism to the bioelectrical membrane for excitable media (spiking, refractoriness, propagating waves), or to Dither-CA, where every state is a palette colour and each cell regulates the mean colour of its neighbourhood toward a target picture — a solid, a gradient, or an uploaded image. Set Paint layer to Target field T(c) and Target mode to Painted field to draw the setpoint itself with a freehand brush, line, rectangle or text stamp, or choose Target mode → Text field T(c) to grow multi-line text that is auto-centred and auto-fitted to a chosen percentage of the grid. Space = play/pause · S = step · R = reset · click/drag the grid to paint (shift-drag erases). Use Colours to recolour every state, overlay and grid line (palettes included), and Embed widget in the side panel to generate a copy-pasteable snippet that runs the current configuration — colours included — on any page.