Set a custom unit for unitless properties

[thecrowkeep]

I rarely write styles with px in mind, I usually want to use r/em units for accessibility reasons, and px is only ever an override to keep a dimension consistent regardless of font size (for example horizontal padding on text).

With how rarely I use px, the unitless properties feature is pointless for me, but I would totally use it if rem was postfixed instead!

Maybe something like this for the sprinkles package:

import {defineProperties, createSprinkles } from '@vanilla-extract/sprinkles';

const properties = defineProperties({
    defaultUnits: "rem"
});

export const sprinkles = createSprinkles(properties);
export type Sprinkles = Parameters<typeof sprinkles>[0];

[nksfrank]

I would love to also be able to customise the unitless unit somehow.