Causes the color values in all children to be interpreted as RGB colors.
:max-r - Range for red (number between 0 and 255)
:max-g - Range for green (number between 0 and 255)
:max-b - Range for blue (number between 0 and 255)
:max-a - Range for alpha (number between 0 and 255)
[:rgb
{:max-r 64, :max-g 64, :max-b 64}
[:fill
{:colors [20 50 70]}
[:rect {:x 10, :y 10, :width 70, :height 70}]]]