Variables without opacity

[FerVillanuevas]

Describe the bug
First time trying v5, everything its amazing. just found this issue or maybe miss configuration on my project, but variables cant have opacity.

Reproduction
Please see our contribution guide: https://github.com/FerVillanuevas/nativewind

[marklawlor]

TailwindCSS is outputting the following CSS

.bg-destructive\/10 {
  background-color: var(--destructive);
  @supports (color: color-mix(in lab, red, red)) {
    background-color: color-mix(in oklab, var(--destructive) 10%, transparent);
  }
}

Because React Native doesn't have a color-mix function, the rules in @supports() are ignored, hence you only receive the non-transparent version.

I'll have a think about this, but I think the only solution might be asking uses to add a color-mix polyfill (~65KB) to their app.

This works for non-variable values because the color-mix() value is calculated at build time.

[marklawlor]

WIP PR #208