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tailwind-css-v4

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Reference for Tailwind CSS v4 syntax and the differences from v3.x. Use when configuring Tailwind (CSS-first @theme config, @import "tailwindcss"), using new v4 features (container queries, 3D transforms, gradients, composable variants, @utility/@variant/@plugin), or migrating v3 patterns. This repo is on v4 — do NOT emit v3 syntax like tailwind.config.js, @tailwind directives, or bg-gradient-*.

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Tailwind CSS v4

Core Changes

  • CSS-first configuration: Configuration is now done in CSS instead of JavaScript

    • Use @theme directive in CSS instead of tailwind.config.js

    • Example:

      @import "tailwindcss";

@theme {
  --font-display: "Satoshi", "sans-serif";
  --breakpoint-3xl: 1920px;
  --color-avocado-500: oklch(0.84 0.18 117.33);
  --ease-fluid: cubic-bezier(0.3, 0, 0, 1);
}

  • Legacy tailwind.config.js files can still be imported using the @config directive:

    @import "tailwindcss";
@config "../../tailwind.config.js";

  • CSS import syntax: Use @import "tailwindcss" instead of @tailwind directives

    • Old: @tailwind base; @tailwind components; @tailwind utilities;
    • New: @import "tailwindcss";

  • Package changes:

    • PostCSS plugin is now @tailwindcss/postcss (not tailwindcss)
    • CLI is now @tailwindcss/cli
    • Vite plugin is @tailwindcss/vite
    • No need for postcss-import or autoprefixer anymore

  • Native CSS cascade layers: Uses real CSS @layer instead of Tailwind's custom implementation

Theme Configuration

  • CSS theme variables: All design tokens are available as CSS variables

    • Namespace format: --category-name (e.g., --color-blue-500, --font-sans)
    • Access in CSS: var(--color-blue-500)
    • Available namespaces:
      • --color-* : Color utilities like bg-red-500 and text-sky-300
      • --font-* : Font family utilities like font-sans
      • --text-* : Font size utilities like text-xl
      • --font-weight-* : Font weight utilities like font-bold
      • --tracking-* : Letter spacing utilities like tracking-wide
      • --leading-* : Line height utilities like leading-tight
      • --breakpoint-* : Responsive breakpoint variants like sm:*
      • --container-* : Container query variants like @sm:* and size utilities like max-w-md
      • --spacing-* : Spacing and sizing utilities like px-4 and max-h-16
      • --radius-* : Border radius utilities like rounded-sm
      • --shadow-* : Box shadow utilities like shadow-md
      • --inset-shadow-* : Inset box shadow utilities like inset-shadow-xs
      • --drop-shadow-* : Drop shadow filter utilities like drop-shadow-md
      • --blur-* : Blur filter utilities like blur-md
      • --perspective-* : Perspective utilities like perspective-near
      • --aspect-* : Aspect ratio utilities like aspect-video
      • --ease-* : Transition timing function utilities like ease-out
      • --animate-* : Animation utilities like animate-spin

  • Simplified theme configuration: Many utilities no longer need theme configuration

    • Utilities like grid-cols-12, z-40, and opacity-70 work without configuration
    • Data attributes like data-selected:opacity-100 don't need configuration

  • Dynamic spacing scale: Derived from a single spacing value

    • Default: --spacing: 0.25rem
    • Every multiple of the base value is available (e.g., mt-21 works automatically)

  • Overriding theme namespaces:

    • Override entire namespace: --font-*: initial;
    • Override entire theme: --*: initial;

New Features

  • Container query support: Built-in now, no plugin needed

    • @container for container context
    • @sm:, @md:, etc. for container-based breakpoints
    • @max-md: for max-width container queries
    • Combine with @min-md:@max-xl:hidden for ranges

  • 3D transforms:

    • transform-3d enables 3D transforms
    • rotate-x-*, rotate-y-*, rotate-z-* for 3D rotation
    • scale-z-* for z-axis scaling
    • translate-z-* for z-axis translation
    • perspective-* utilities (perspective-near, perspective-distant, etc.)
    • perspective-origin-* utilities
    • backface-visible and backface-hidden

  • Gradient enhancements:

    • Linear gradient angles: bg-linear-45 (renamed from bg-gradient-*)
    • Gradient interpolation: bg-linear-to-r/oklch, bg-linear-to-r/srgb
    • Conic and radial gradients: bg-conic, bg-radial-[at_25%_25%]

  • Shadow enhancements:

    • inset-shadow-* and inset-ring-* utilities
    • Can be composed with regular shadow-* and ring-*

  • New CSS property utilities:

    • field-sizing-content for auto-resizing textareas
    • scheme-light, scheme-dark for color-scheme property
    • font-stretch-* utilities for variable fonts

New Variants

  • Composable variants: Chain variants together

    • Example: group-has-data-potato:opacity-100

  • New variants:

    • starting variant for @starting-style transitions
    • not-* variant for :not() pseudo-class
    • inert variant for inert attribute
    • nth-* variants (nth-3:, nth-last-5:, nth-of-type-4:, nth-last-of-type-6:)
    • in-* variant (like group-* but without adding group class)
    • open variant now supports :popover-open
    • ** variant for targeting all descendants

Custom Extensions

  • Custom utilities: Use @utility directive

    @utility tab-4 {
  tab-size: 4;
}

  • Custom variants: Use @variant directive

    @variant pointer-coarse (@media (pointer: coarse));
@variant theme-midnight (&:where([data-theme="midnight"] *));

  • Plugins: Use @plugin directive

    @plugin "@tailwindcss/typography";

Breaking Changes

  • Removed deprecated utilities:

    • bg-opacity-* → Use bg-black/50 instead
    • text-opacity-* → Use text-black/50 instead
    • And others: border-opacity-*, divide-opacity-*, etc.

  • Renamed utilities:

    • shadow-sm → shadow-xs (and shadow → shadow-sm)
    • drop-shadow-sm → drop-shadow-xs (and drop-shadow → drop-shadow-sm)
    • blur-sm → blur-xs (and blur → blur-sm)
    • rounded-sm → rounded-xs (and rounded → rounded-sm)
    • outline-none → outline-hidden (for the old behavior)

  • Default style changes:

    • Default border color is now currentColor (was gray-200)
    • Default ring width is now 1px (was 3px)
    • Placeholder text now uses current color at 50% opacity (was gray-400)
    • Hover styles only apply on devices that support hover (@media (hover: hover))

  • Syntax changes:

    • CSS variables in arbitrary values: bg-(--brand-color) instead of bg-[--brand-color]
    • Stacked variants now apply left-to-right (not right-to-left)
    • Use CSS variables instead of theme() function

Advanced Configuration

  • Using a prefix:

    @import "tailwindcss" prefix(tw);
    • Results in classes like tw:flex, tw:bg-red-500, tw:hover:bg-red-600

  • Source detection:

    • Automatic by default (ignores .gitignore files and binary files)
    • Add sources: @source "../node_modules/@my-company/ui-lib";
    • Disable automatic detection: @import "tailwindcss" source(none);

  • Legacy config files:

    @import "tailwindcss";
@config "../../tailwind.config.js";

  • Dark mode configuration:

    @import "tailwindcss";
@variant dark (&:where(.dark, .dark *));

  • Container customization: Extend with @utility

    @utility container {
  margin-inline: auto;
  padding-inline: 2rem;
}

  • Using @apply in Vue/Svelte:

    <style>
  @import "../../my-theme.css" theme(reference);
  /* or */
  @import "tailwindcss/theme" theme(reference);

  h1 {
    @apply text-2xl font-bold text-red-500;
  }
</style>