hsl() function in CSS for setting HSL colors has 2 syntaxes available: Space-separated and
comma-separated. It also allows to optionally provide an alpha value to define a HSLA color.
hsl(hue saturation lightness / alpha)
hsl(hue, saturation, lightness, alpha)
Hue is an angle in degrees, although other units like
turn are supported as well.
Saturation and lightness are both given as percentages.
Alpha (optional) can be specified as either a percentage or number from 0 to 1
hsl(255deg 69% 42%); hsl(255deg 69% 42% / 0.75); hsl(255deg, 69%, 42%); hsl(255deg, 69%, 42%, 0.75);
See MDN for more details