hex#000000
rgb0, 0, 0
decimal0
Six bands, base: 16, one per hex digit of a 24-bit colour.
The top band is 16^0, the low nibble of blue; the bottom is
16^5, the high nibble of red. Because the base sets the tick
rhythm as well as the step size, one major tick is exactly one digit —
sweep a band through a full major interval and it carries into the next.