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TailwindCSS v4 Patterns

Overview

TailwindCSS v4 introduces a CSS-first approach, eliminating the need for JavaScript configuration files. All customization happens directly in CSS using new directives.

Key Changes from v3 to v4

Browser Support

TailwindCSS v4 requires modern browsers:

• Safari 16.4+
• Chrome 111+
• Firefox 128+

Important: No CSS preprocessors (Sass/Less) needed - Tailwind IS the preprocessor.

Documentation Index

Core Documentation

Configuration Reference

CSS Features

Customization

CSS-First Configuration

Basic Setup

/* src/index.css */
@import "tailwindcss";

This single import replaces the v3 directives (@tailwind base, @tailwind components, @tailwind utilities).

@theme Directive - Design Tokens

The @theme directive defines design tokens as CSS custom properties:

@import "tailwindcss";

@theme {
  /* Colors */
  --color-primary: hsl(221 83% 53%);
  --color-primary-dark: hsl(224 76% 48%);
  --color-secondary: hsl(215 14% 34%);
  --color-accent: hsl(328 85% 70%);

  /* With oklch (modern color space) */
  --color-success: oklch(0.723 0.191 142.5);
  --color-warning: oklch(0.828 0.189 84.429);
  --color-error: oklch(0.637 0.237 25.331);

  /* Typography */
  --font-display: "Satoshi", "sans-serif";
  --font-body: "Inter", "sans-serif";
  --font-mono: "JetBrains Mono", "monospace";

  /* Spacing */
  --spacing-page: 2rem;
  --spacing-section: 4rem;

  /* Custom breakpoints */
  --breakpoint-xs: 480px;
  --breakpoint-3xl: 1920px;

  /* Animation timing */
  --ease-spring: cubic-bezier(0.68, -0.55, 0.265, 1.55);
  --duration-fast: 150ms;
  --duration-normal: 300ms;
}

Generated utilities from above:

• Colors: bg-primary, text-primary-dark, border-accent
• Fonts: font-display, font-body, font-mono
• Animations: ease-spring, duration-fast

@theme inline Pattern

Use @theme inline to reference existing CSS variables without generating new utilities:

/* Define CSS variables normally */
:root {
  --background: oklch(1 0 0);
  --foreground: oklch(0.145 0 0);
  --card: oklch(1 0 0);
  --primary: oklch(0.205 0 0);
}

.dark {
  --background: oklch(0.145 0 0);
  --foreground: oklch(0.985 0 0);
  --primary: oklch(0.985 0 0);
}

/* Map to Tailwind utilities */
@theme inline {
  --color-background: var(--background);
  --color-foreground: var(--foreground);
  --color-card: var(--card);
  --color-primary: var(--primary);
}

When to use @theme inline:

• Theming with CSS variables (light/dark mode)
• Shadcn/ui integration
• Dynamic theme switching

@source Directive - Content Detection

@import "tailwindcss";

/* Default: Tailwind scans all git-tracked files */

/* Add additional sources */
@source "../node_modules/my-ui-library/src/**/*.{html,js}";
@source "../shared-components/**/*.tsx";

/* Safelist specific utilities */
@source inline("bg-red-500 text-white p-4");

@custom-variant - Custom Variants

@import "tailwindcss";

/* Dark mode variant (class-based) */
@custom-variant dark (&:is(.dark *));

/* RTL variant */
@custom-variant rtl ([dir="rtl"] &);

/* Print variant */
@custom-variant print (@media print { & });

/* Hover on desktop only */
@custom-variant hover-desktop (@media (hover: hover) { &:hover });

@utility - Custom Utilities

@import "tailwindcss";

/* Text balance utility */
@utility text-balance {
  text-wrap: balance;
}

/* Scrollbar hide */
@utility scrollbar-hide {
  -ms-overflow-style: none;
  scrollbar-width: none;
  &::-webkit-scrollbar {
    display: none;
  }
}

/* Flex center shorthand */
@utility flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}

@plugin - Plugin Configuration

@import "tailwindcss";

/* Load a plugin */
@plugin "@tailwindcss/typography";
@plugin "@tailwindcss/forms";
@plugin "@tailwindcss/container-queries";

/* Plugin with options */
@plugin "@tailwindcss/typography" {
  className: prose;
}

@config - Legacy JS Configuration

When you need JS configuration (rare in v4):

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

Vite Integration

Installation

npm install tailwindcss @tailwindcss/vite

Vite Configuration

// vite.config.ts
import tailwindcss from "@tailwindcss/vite"
import react from "@vitejs/plugin-react"
import path from "path"
import { defineConfig } from "vite"

export default defineConfig({
  plugins: [react(), tailwindcss()],
  resolve: {
    alias: {
      "@": path.resolve(__dirname, "./src"),
    },
  },
})

CSS Entry Point

/* src/index.css */
@import "tailwindcss";

@theme {
  /* Your design tokens */
}

TypeScript Path Aliases

// tsconfig.json
{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "@/*": ["./src/*"]
    }
  }
}

Modern CSS Features with Tailwind v4

Native CSS Variables

Tailwind v4 uses native CSS variables without wrapper functions:

/* v3 - Required hsl wrapper */
--primary: 221 83% 53%;
background-color: hsl(var(--primary));

/* v4 - Direct CSS value */
--color-primary: hsl(221 83% 53%);
/* Used as: bg-primary */

oklch Color Format

@theme {
  /* oklch: lightness, chroma, hue */
  --color-brand: oklch(0.65 0.2 250);
  --color-brand-light: oklch(0.85 0.15 250);
  --color-brand-dark: oklch(0.45 0.25 250);
}

Benefits of oklch:

• Perceptually uniform
• Consistent lightness across hues
• Better for generating color scales
• Native browser support

Container Queries

<!-- Parent needs @container -->
<div class="@container">
  <!-- Child responds to container width -->
  <div class="grid grid-cols-1 @md:grid-cols-2 @lg:grid-cols-3">
    <!-- Content -->
  </div>
</div>

/* Named containers */
.sidebar {
  container-name: sidebar;
  container-type: inline-size;
}

/* Target named container */
@container sidebar (min-width: 300px) {
  .nav-item { /* expanded styles */ }
}

:has() Pseudo-Class

<!-- Style parent based on child state -->
<label class="group has-[:invalid]:border-red-500 has-[:focus]:ring-2">
  <input type="email" class="peer" />
</label>

/* Card with image gets different padding */
.card:has(> img) {
  @apply p-0;
}

/* Form with invalid fields */
.form:has(:invalid) {
  @apply border-red-500;
}

Native CSS Nesting

.card {
  @apply rounded-lg bg-white shadow-md;

  .header {
    @apply border-b p-4;
  }

  .content {
    @apply p-6;
  }

  &:hover {
    @apply shadow-lg;
  }

  &.featured {
    @apply border-2 border-primary;
  }
}

Utility Patterns

Responsive Design (Mobile-First)

<!-- Breakpoints: sm(640px), md(768px), lg(1024px), xl(1280px), 2xl(1536px) -->
<div class="
  p-4 text-sm               /* Mobile */
  sm:p-6 sm:text-base       /* Tablet */
  lg:p-8 lg:text-lg         /* Desktop */
  2xl:p-12 2xl:text-xl      /* Large screens */
">

State Variants

<!-- Hover, focus, active -->
<button class="
  bg-primary text-white
  hover:bg-primary-dark
  focus:ring-2 focus:ring-primary focus:ring-offset-2
  active:scale-95
  disabled:opacity-50 disabled:cursor-not-allowed
">

<!-- Group hover -->
<div class="group">
  <span class="group-hover:underline">Label</span>
  <span class="opacity-0 group-hover:opacity-100">Icon</span>
</div>

<!-- Peer focus -->
<input class="peer" />
<span class="invisible peer-focus:visible">Hint text</span>

Dark Mode

Strategy 1: Class-based (recommended)

@custom-variant dark (&:is(.dark *));

<html class="dark">
<body class="bg-white dark:bg-gray-900 text-black dark:text-white">

Strategy 2: Media query

@custom-variant dark (@media (prefers-color-scheme: dark) { & });

Animation Utilities

<!-- Built-in animations -->
<div class="animate-spin" />
<div class="animate-pulse" />
<div class="animate-bounce" />

<!-- Custom animation -->
<div class="animate-[fadeIn_0.5s_ease-out]" />

@theme {
  --animate-fade-in: fadeIn 0.5s ease-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-10px); }
  to { opacity: 1; transform: translateY(0); }
}

Size Utility (v4)

<!-- v3: Two classes -->
<div class="w-10 h-10">

<!-- v4: Single class -->
<div class="size-10">

Best Practices

When to Use @apply

Use @apply sparingly for true component abstraction:

/* Good: Repeated pattern across many components */
@layer components {
  .btn-primary {
    @apply px-4 py-2 bg-primary text-white rounded-md;
    @apply hover:bg-primary-dark focus:ring-2 focus:ring-primary;
    @apply disabled:opacity-50 disabled:cursor-not-allowed;
    @apply transition-colors duration-fast;
  }
}

/* Bad: One-off styling (just use utilities in HTML) */
.my-special-div {
  @apply mt-4 p-6 bg-gray-100; /* Just put these in className */
}

Rule: Only extract patterns when reused 3+ times.

Design Token Naming

@theme {
  /* Semantic naming (preferred) */
  --color-primary: hsl(221 83% 53%);
  --color-primary-foreground: hsl(0 0% 100%);

  /* Not: --color-blue-600: ... */

  /* Scale naming when needed */
  --color-gray-50: oklch(0.985 0 0);
  --color-gray-100: oklch(0.970 0 0);
  --color-gray-900: oklch(0.145 0 0);
}

Performance

1. Use Vite plugin - Automatic dead code elimination
2. Avoid dynamic class names - Static analysis can't optimize them
3. Purge unused styles - Automatic with proper @source config

<!-- Good: Static class names -->
<div class={isActive ? "bg-primary" : "bg-gray-100"}>

<!-- Bad: Dynamic class construction -->
<div class={`bg-${color}-500`}> <!-- Can't be purged -->

CSS Layers Order

Tailwind v4 uses CSS cascade layers:

1. @layer base - Reset, typography defaults
2. @layer components - Reusable components
3. @layer utilities - Utility classes (highest priority)

Custom styles should go in appropriate layers:

@layer components {
  .card { /* component styles */ }
}

@layer utilities {
  .text-shadow { /* utility styles */ }
}

Related Skills

• shadcn-ui - Component library using Tailwind (CSS variables, theming)
• css-modules - Alternative: scoped CSS for complex components
• react-typescript - React patterns with Tailwind className
• design-references - Design system guidelines (Tailwind UI reference)

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