They're more like guidelines than actual rules.
On another note, the bright red, orange, red-orange and red-yellow and orange-yellow and yellow jewel tones on our street have begun fading to pink. I am reminded of the way an incandescent bulb glows after the power is switched off, or the way embers glow when the fire dies. Shockingly bright for a time, and then dull and low, and then black. Cary Street, which I drive to work, is redder than ours, and the way across the river is more yellow. Something in the soil, perhaps.