## Why?
While inspecting a Tailwind-powered site, I noticed selectors like
```css
.inset-0{inset:calc(var(--spacing) * 0)}
.inset-x-0{inset-inline:calc(var(--spacing) * 0)}
.top-0{top:calc(var(--spacing) * 0)}
```
which seem a bit silly, not to mention more complex for the end-user
device parsing the CSS.
## Summary
This PR adjusts helpers to not generate `calc(... * 0)` expressions.
https://github.com/tailwindlabs/tailwindcss/pull/19095 does a similar
thing on CSS AST, but that doesn't run during the build proper.
## Test plan
Ran `pnpm build && pnpm test && pnpm test:integration`. (Some unrelated
tests failed on my machine, hopefully less in CI.)
---------
Co-authored-by: Robin Malfait <malfait.robin@gmail.com>
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