CSS was introduced to the web all the way back in 1996. At the time, most computer monitors were pretty terrible. The colors of CSS — whether defined with the RGB, HSL, or hexadecimal format — catered to the monitors of the time, all within the sRGB colorspace.
Most newer devices have a wide-gamut display. A gamut is the range of colors that can be displayed. A wide-gamut display is capable of showing more colors than sRGB. They use the … Read article “The Expanding Gamut of Color on the Web”