alpha()The alpha() CSS function computes a relative color value by adjusting the opacity of an origin color.color-typesColor typeslimitedhttps://drafts.csswg.org/css-color-5/#relative-alphahttps://developer.mozilla.org/docs/Web/CSS/Reference/Values/color_value/alphacss.types.color.alphahttps://nowyoucanuse.com/features--alpha.html