Allow for a minute or longer
the colors to impress you.

When you scroll down:

Center the 3 spheres in your browser window.

Look in the white space between the three circles, do not observe the color circles directly, allow your eyes maybe to become unsharp (out of focus), and I promise, that you will change your opinion about this simple picture and it's colors.

You may need to select reload/refresh in your browser if the circles don't move.

enjoy the colors and your perceptions:

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Explanation:

Every circle is switching between the primary color and it's complementary (or secondary) color.

You can make an experiment:

take a white paper with a violet symbol on it and look at it for a while, then take a complete white paper and look at it or look at a white wall, you will see that an imaginary yellow symbol appears now. Of course this effect will happen also vice versa.

or watch it here: