The upper half region is filled with hsl color.
The lower half region is filled with rgb color equivalent.
This is javascript implementation of wikipedia.
function hsl2rgb(h, s, l) {
s = s / 100;
l = l / 100;
let c = (1 - Math.abs(2*l-1)) * s; // chroma
h = h / 60;
let x = c * (1 - Math.abs((h % 2) - 1));
let r = 0, g = 0, b = 0;
if (h < 1)
r = c, g = x;
else if (h < 2)
r = x, g = c;
else if (h < 3)
g = c, b = x;
else if (h < 4)
g = x, b = c;
else if (h < 5)
r = x, b = c;
else
r = c, b = x;
let m = l - c/2;
return {r: (r+m)*255, g: (g+m)*255, b: (b+m)*255};
}