{"id":655,"slug":"tailwind-v4-oxide-stable-jan-2025","title":"Tailwind v4 (January 2025) — Oxide engine; CSS-first @theme config; ~3.5× faster full builds, ~8× faster incrementals","kind":"reference","scope":"business","status":"current","audiences":["claude-code","candid-team"],"topics":["css-architecture","build-tooling"],"reference_body":"**Claim:** Tailwind v4 released January 2025. Per Tailwind Labs' Catalyst-project benchmark (tailwindcss.com/blog/tailwindcss-v4): *\"full rebuilds to be over 3.5x faster, and incremental builds to be over 8x faster\"*; median full build dropped from 378ms to 100ms; *\"incremental builds that don't actually need to compile any new CSS — these builds are over 100x faster and complete in microseconds.\"*\n\n**Confidence:** Verified for the qualitative finding (substantially faster, microsecond no-op incrementals); exact multiplier varies by project shape.\n\n**Key changes:**\n\n- **Oxide engine** (Rust-based).\n- **CSS-first config** via `@theme` directive — no more `tailwind.config.js`.\n- **Native cascade layers** (`@layer`).\n- **Auto content detection** — no more `content` array.\n\n**For Candid:** standardize Tailwind v4 with `@theme` config on every new project. **Do not migrate existing v3 projects retroactively** — 4-8 hours per project with custom plugins. Adopt-for-new is the right policy.\n\n**Counter-position worth holding:** for static marketing sites with a strong bespoke design system, hand-written modern CSS (nesting + container queries + `@scope` + custom properties + `light-dark()`) is now genuinely viable and ships smaller. Take this position on projects where the design is highly bespoke.","rationale_body":null,"metadata":null,"links":{"outgoing":[{"slug":"rule-prefer-astro-cloudflare-default-marketing-site","title":"RULE: Default stack for new marketing-site work is Astro 5/6 + Tailwind v4 on Cloudflare Pages","kind":"rule","scope":"business","link_type":"relates-to"}],"incoming":[]},"created_at":"2026-05-22T21:24:18.313Z","updated_at":"2026-05-22T21:24:18.313Z"}