[v4] Support --opacity-* theme configuration

[Eirmas]

In Tailwind 3, opacity was a part of the theme configuration where you could override/extend the opacity levels with your own.

It would be nice if we could do this in version 4 too.

@theme {
  --opacity-disabled: 38%;
}

[wongjn]

You can

[Eirmas]

Huh, I see now that it's supported, but I've discovered something weird.

I've split my variables into their own files just to keep things organized and easy to find.
It seems like the order I import them into my index.scss file matters?

For some reason, all of my variables imported below my breakpoints are ignored. Maybe I should open an issue?

@wongjn

[Eirmas]

I believe I found the issue: https://play.tailwindcss.com/EMnyXd42Ot

I was using variables inside my theme without using the "inline" keyword. That broke everything. Whoops!