prettier/tests/css_color/whitespace-syntax.css

.foo {
    color: rgba(51 170 51 / 0.4);
    color: rgba(51 170 51 / 40%);
    color: hsl(270 60% 50% / .15);
    color: hsla(240 100% 50% / .05);
    color: hsla(240 100% 50% / 5%);
}