Not the day-to-day CSS-first configuration reference (tailwindcss-core owns @theme/@utility/@variant usage) and not a utility-class lookup (the category skills own that).

Tailwind CSS v4.1 Core

Documentation

• CSS theme variables, design tokens, customization -> tailwindcss-core
• Directives (@utility, @variant, @theme, @apply) -> tailwindcss-core
• Custom utilities and variants -> tailwindcss-custom-styles
• Content detection (@source scanning) -> tailwindcss-core
• Migration from v3 to v4 -> see "v3 → v4 Breaking Changes" section below

Quick Reference - @theme Namespaces