https://www.w3schools.com/colors/colors_hsl.asp
HSL Colors
HSL color values are supported in Edge, Chrome, Firefox, Safari, Opera 10+, and in IE9+.
HSL stands for Hue, Saturation, and Lightness.
HSL color values are specified with:
hsl(hue, saturation, lightness)
Hue
Hue is a degree on the color wheel from 0 to 360. 0 (or 360) is red, 120 is green, 240 is blue.
Saturation
Saturation can be described as the intensity of a color. It is a percentage value from 0% to 100%.
100% is full color, no shades of gray.
50% is 50% gray, but you can still see the color.
0% is completely gray; you can no longer see the color.
Lightness
The lightness of a color can be described as how much light you want to give the color, where 0% means no light (dark), 50% means 50% light (neither dark nor light), and 100% means full light.
Try it Yourself
HSL color values are supported in all major browsers.
Example
<style>
div {
background-color: hsl(170, 50%, 50%);
color: hsl(0, 50%, 50%);
}
</style>
HSLA Color Values
HSLA color values are an extension of HSL color values, with an Alpha channel - which specifies the opacity for a color.
An HSLA color value is specified with:
hsla(hue, saturation, lightness, alpha)
The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (not transparent at all):
Example
<h1 style="background-color:hsla(120, 100%, 50%, 0.2);">hsla(0, 100%, 50%, 0.2)</h1>
<h1 style="background-color:hsla(120, 100%, 50%, 0.4);">hsla(0, 100%, 50%, 0.4)</h1>
<h1 style="background-color:hsla(120, 100%, 50%, 0.6);">hsla(0, 100%, 50%, 0.6)</h1>
<h1 style="background-color:hsla(120, 100%, 50%, 0.8);">hsla(0, 100%, 50%, 0.8)</h1>