Modern CSS features that replace Sass, PostCSS plugins and JavaScript hacks: nesting, :has(), container queries, subgrid and more, checked in September 2026.

Big stylesheets used to get their order from a folder structure and a build tool. Reset first, then base styles, then components, then utilities, plus a rule that nobody adds !important before the third code review.

@layer writes that order into the CSS itself:

A rule in a later layer beats any rule in an earlier layer, whatever its specificity. .p-0 wins over .card .button because utilities comes after components, and the order of the files no longer matters.