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).