Green (#008000) is a medium, highly saturated green hue. The CSS green keyword is a medium green, darker than pure sRGB green (#00FF00, which CSS calls lime).
In RGB it is made of 0 red, 128 green and 0 blue. Its HSL hue angle is 120° with 100% saturation and 25% lightness, while its perceptual OKLCH lightness is 52% with a chroma of 0.177. For print, a starting CMYK mix is 100% cyan, 0% magenta, 100% yellow and 50% black.
As a text color on white, Green has a contrast ratio of 5.14:1, which passes WCAG AA for normal text. On black it reaches 4.09:1 and passes AA only for large text. If you use Green as a background, put white text on it. The APCA lightness contrast is Lc 29 for black text and Lc -80 for white text.
Its perceptual complement is #963BA3, close to plum. Colors that look most similar are forest green, sea green, olive. People with red-green color blindness see green quite differently (ΔE 12), so do not rely on it alone to signal meaning.