Anchor positioning, read and not used

A CSS feature that solves a real problem, available in one engine, evaluated and deferred.

.tooltip {
  position: absolute;
  position-anchor: --trigger;
  position-area: block-start;
  position-try-fallbacks: flip-block, flip-inline;
}

/* what it replaces: a positioning library, a scroll
   listener, a resize observer and a collision
   algorithm — about 8 KB. */

The fallback syntax is the part that makes this genuinely better than the JavaScript it replaces, because collision handling is declarative rather than a loop. Single-engine support means the JavaScript has to stay, and running both is worse than running one — so this is a note about what to delete in two years rather than a change.