Black hsl(0,0%,0%). Red hsl(0,100%,50%).
Green hsl(120,100%,50%). Blue hsl(240,100%,50%).

Black hsla(0,0%,0%,0.5). Red hsla(0,100%,50%,0.5).
Green hsla(120,100%,50%,0.5). Blue hsla(240,100%,50%,0.5).