The smallest four-colouring mosaic
Click on the faces to color them. To change the color, click on the same region again
In mathematics, the four color theorem states that, given any separation of a plane into continuous regions, producing a figure called a map, no more than four colors are required to color the regions of the map so that no two adjacent regions have the same color.
Updated version using Coloreando el mapa by Ignacio Larrosa Cañestro.