Firefox 150: let the browser choose image size

Information already in the layout

In our retrospective April review, Firefox 150, released on April 21, 2026, supports sizes="auto" for lazy-loaded images. The browser can use their calculated size to choose a resource from srcset. MDN notes.

Avoid competing descriptions

A catalog page often describes card width in CSS, then repeats similar assumptions in image attributes. For developers, the interest lies in reducing the risk of these descriptions drifting apart after a grid change. A narrow screen and a large display provide useful checkpoints; pixel density should also be part of the comparison.

Measure what gets downloaded

Support alone does not guarantee a lighter page. Check the resource actually received and its visual quality in browsers used by the intended audience. The main image visible immediately deserves a separate assessment: this case concerns lazy loading. A network check on a representative page helps distinguish simpler markup from a real benefit for visitors.