sizes="auto" just landed in Gecko and WebKit, solving the 14-year timing problem at the heart of responsive images in HTML.
Key Takeaways
The root flaw in srcset/sizes was timing: browsers request images before knowing layout, forcing authors to pre-calculate sizes with fragile calc() expressions.
sizes="auto" requires loading="lazy" and defers the size decision until layout is known, eliminating manual sizes math entirely.
Gecko and WebKit patches now align all three major engines (Blink, Gecko, WebKit) behind the auto value in the HTML spec.
The full responsive image pattern collapses to srcset + sizes="auto" + loading="lazy", removing the (min-width: ...) viewport arithmetic most authors got wrong anyway.
Hacker News Comment Review
Commenters are split: some see sizes="auto" as a genuine spec win after years of grinding standards work; others call it closer to a polyfill than a clean solution, noting the syntax still requires srcset descriptors and loading="lazy" as a precondition.
The standards-process angle drew genuine appreciation: one commenter noted that a small group of enthusiasts can still move Google and Apple, even incrementally.
A practical gap was flagged: no mention of image seam carving as a browser-native alternative, which some consider an unresolved part of the responsive image problem.
Notable Comments
@keane: quotes the spec text directly – the timing fix is the stated motivation, and auto is described as reversing the default eager-request behavior.
@mrbluecoat: “feels more like a polyfill than a final industry solution” – shows the syntax still looks verbose in practice.
