Monochromatic

Monochromatic means "one color" or "one hue" (not shades of gray). It can include a set of different shades and tints of that color. For example:

#66CC00

#4C9900

#336600

#FFCCCC

#FF9999

#FF6666

Monochrome color schemes give a sense of being at rest, peaceful, without tension.