by AdamStanislav - uploaded on June 11, 2016, 9:50 pm
Since we are using colors for both, the light and the dark, we simply draw a circle in one color, using Bézier curves with kappa=4*(sqrt(2)-1)/3, counterclockwise.
Then we draw the complementary design, clockwise, in another color of the same hue but darker. We then turn it into a piece of yin-yang leather. For that, we are using standard SVG filters, supported by most but, unfortunately, not all browsers.
All hand-coded SVG, by the way. That’s because math rules the Universe!
I used color.adobe.com/create/color-wheel/ to pick both, the light and the dark, colors.