Green-yellow

Historically, achieving such vibrancy was dangerous, often relying on copper-arsenic pigments like Scheele's Green invented in 1775. These toxic dyes were prevalent in Victorian fashion and wallpaper until they were replaced by safer chemical compounds like Cobalt Green, though the association with sickness remained.

In the 20th century, this specific high-chroma shade found a home in the psychedelic art of the 1960s and the cyber-culture of the 1990s. It became a symbol of rebellion and modernity, moving from the canvas of Impressionist landscapes to the neon signage of urban nightlife.

Psychologically, this color induces high arousal, stimulating the nervous system and effectively combating lethargy. However, it can feel jarring or 'sour' to the eye, creating a sense of anxiety or nausea if used in large, unbroken quantities.

Culturally, it bridges the gap between vitality (like sour citrus) and danger (like radioactive waste symbols). It is frequently used to signal innovation in modern tech branding, suggesting forward momentum, unconventional thinking, and a break from tradition.

While rare in vast landscapes, this shock of color appears distinctly in the warning coloration, or aposematism, of poison dart frogs. It is also seen in the transient glow of bioluminescence found in fireflies or specific deep-sea creatures. In the botanical world, it mimics the burst of new growth on ferns or tendrils before chlorophyll saturation deepens the shade.

In design, this color acts as a powerful accent to direct user attention immediately to specific elements. It is effective for 'Call to Action' buttons or highlights but should never cover large surface areas due to the risk of visual vibration.

Regarding accessibility, you must pair this neon hue with dark hues like black or charcoal to ensure legibility. White text on this background will almost always fail standard contrast ratios, rendering the content unreadable to users with visual impairments.