Tailwind CSS v4 Best Practices

Use Tailwind utilities first. Abstract only when variants justify it.

Goal

Keep styling local, explicit, accessible, and easy to change.

Rules

• Use utility classes directly for simple components.
• Use CVA when a component has 3+ variants and needs type-safe props.
• Use tailwind-variants for slots, compound parts, or complex design systems.
• Avoid @apply for component styles.
• Use @theme for design tokens.
• Use data attributes for component state.
• Keep one styling approach per component family.
• Preserve accessibility on interactive elements.

Tailwind v4 Setup

@import "tailwindcss";

@theme {
  --color-brand-primary: oklch(0.65 0.24 354.31);
  --font-sans: "Inter", sans-serif;
  --radius-button: 0.5rem;
}

Decision Guide

• Pure utilities: 1-2 variants, simple component, no shared API needed.
• CVA: 3+ variants, type-safe props, button-like component.
• tailwind-variants: slots, responsive variants, component composition.
• Custom @utility: rare project-specific utility.
• @apply: avoid unless project convention requires it.

Component Rules

• Keep base layout classes obvious.
• Put state in data-* attributes when it affects styling.
• Use disabled, aria-disabled, and aria-busy correctly.
• Accept className only when extension is intended.
• Merge classes with existing project helper, usually cn.
• Do not hide important design choices behind unclear helpers.

Migration Notes

• shadow-sm became shadow-xs.
• rounded-sm became rounded-xs.
• bg-opacity-50 becomes bg-black/50.
• bg-gradient-to-r becomes bg-linear-to-r.
• border now uses currentColor.
• ring now uses currentColor; use explicit ring width and color.

Flow

1. Check existing component style patterns.
2. Count variants and slots.
3. Pick utilities, CVA, or tailwind-variants.
4. Add tokens through @theme when needed.
5. Model state with attributes.
6. Verify responsive behavior and accessibility.

References

• Tailwind CSS v4 Docs
• CVA (class-variance-authority)
• Tailwind Variants
• shadcn/ui

Output

## Tailwind v4 Decision
- Approach: [utilities/CVA/tailwind-variants]
- Reason: [variant count, slots, or project pattern]
- Tokens: [added or none]
- Accessibility: [states and labels checked]
- Migration notes: [v3 changes or none]