EffCSS Proposes a Third Path Between Runtime and Zero-Runtime CSS-in-JS

The CSS-in-JS ecosystem is currently divided between runtime libraries like Emotion, which regenerate style hashes on the client, and zero-runtime tools like Vanilla Extract, which compile static CSS classes at build time. Runtime approaches retain full dynamism but recompute style identifiers even during hydration, wasting client resources. Zero-runtime tools eliminate that overhead but restrict dynamic styling to CSS custom properties and a fixed set of precompiled selectors. A developer writing on DEV Community argues both approaches share a deeper flaw: they treat the CSS selector as a value derived from the style itself, rather than as an independent artifact. The article proposes a third approach, called EffCSS, which aims to decouple the logical style name from its CSS output to avoid both recomputation and static limitations.