4 CSS FEATURES EVERY FRONT-END DEVELOPER SHOULD KNOW IN 2026

Summary from the TLDR Dev newsletter

CSS recently shipped `sibling-index()` and `sibling-count()` for creating staggered animations and other calculations based on an element's position relative to its siblings. `@container scroll-state()` is new and can be used for querying specific scroll states like 'stuck' or 'snapped', and `text-box` for control over typographic whitespace. `typed attr()` is an advanced function that allows HTML attributes to be used in CSS with type checking and fallbacks.