Topic
Uneven engine support for new CSS features and safe rollout via default behaviour and @supports feature queries.
TC39's iterator helpers are Baseline as of September 2026, so lazy chains run without a polyfill from Chrome 122 and Node 22 upward, while the teams reporting the 40-60% memory saving attached to them are unnamed.
Reality
TypeScript's DOM types only cover APIs shipped by two browser engines, so startViewTransition, Long Animation Frames and fetchLater() all fail to compile. modern-web-types regenerates the same libraries at a one-engine threshold.
Reality
A dev.to teardown of Apple's spec sheet puts both of the new foldable's displays near the same 1:1.42 shape. The CSS spec that reports a fold runs only in Chromium, so Safari code has to work the state out from width and height.
Reality
SoVeryBright wraps the ISO 21496-1 gain-map standard in an upload box. Whether the extra brightness reaches anybody depends on what your CDN and CMS do to the bytes in transit.
Reality
A dev.to guide walks the failure modes: same-origin policy blocks parent.location, referrer policy empties document.referrer, and nested frames name the wrong site. ancestorOrigins is the tier left.
Reality
Chromium 129 shipped interpolate-size, which resolves auto to a real number before a transition starts. The guessed ceiling and the scrollHeight bookkeeping are both deletable.
Reality