fix(tooltip): cap the content width at the space Radix measures

[tmccoy14]

Why

TooltipContent sets no max-width at all, so every consumer has to cap it themselves or let long content run the tooltip off screen. Guardian's studio app was doing exactly that at eight call sites behind a token of its own — this pulls the default into the design system so it doesn't have to.

Found while reviewing a tooltip sweep in guardian, where the app-level version of this token was silently broken (see below).

The @theme inline part matters

The value has to live in the @theme inline block. With a plain @theme, Tailwind declares the token on :root and emits max-width: var(--container-tooltip). A var() inside a custom property is substituted where that property is declared — on :root, where --radix-tooltip-content-available-width doesn't exist — so it collapses to the 100vw fallback before it ever reaches a tooltip, and the Radix measurement is a bystander.

Compiled both ways to confirm:

@theme         →  .tooltip-content { max-width: var(--container-tooltip) }   /* var resolved on :root */
@theme inline  →  .tooltip-content { max-width: min(32rem, var(--radix-tooltip-content-available-width, 100vw)) }

Inlined, the declaration lands on the content element — the same element Radix sets the variable on — and the measurement survives, collision padding included. Verified in the built dist/tooltip.module.module.css.module.css.

This is the same pattern the component already uses for @apply origin-(--radix-tooltip-content-transform-origin).

Overriding

.tooltip-content compiles unlayered, so it beats @layer utilities regardless of order — a plain max-w-* utility won't win, and an override needs max-w-md!. That's already the convention consumers hit with this component (guardian writes text-xs! on these very tooltips), but it wasn't written down, so the docs now cover both that and the --container-tooltip token for a global change.

Note for consumers

This is a behavior change: any app relying on unbounded tooltip width now gets a 32rem cap. Guardian is unaffected — it already caps at exactly this value in all eight places, and those come out once this publishes.

Docs updated with a new Width section on the Tooltip page.