Color Fan Illusion

Open fullscreen view @keyframes spin { 0% { rotate: 0; } 100% { rotate: 360deg;} } :root { background: #777; &::before { content: ""; width: 50vmin; aspect-ratio: 1; border-radius: 50%; position: absolute; top: 50%; left: 50%; translate: -50% -50%; background: radial-gradient(farthest-side, #000 2%, #fff 0 3.5%, red 0 20%, #0000 0 80%, lime 0), repeating-conic-gradient(#0000 0 60deg, red 0 120deg), lime; animation: spin 3s linear infinite; } }

About This Illusion

If you focus on the black dot, the illustration may appear to develop a darker greenish or brownish border. However, the colors never change.

This optical illusion requires only two gradients: a conic gradient for the fan-shaped arms and a radial gradient for the circles and discs.

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