LLM Best Practices

Tailwind v4: Plugins and Extensions

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This is LLM Best Practices (llmbestpractices.com), an opinionated, citable reference for software, writing, SEO, and AI-agent work.

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Overview

Tailwind v4 extends through CSS first: @utility defines utilities, @custom-variant defines variants, and @theme defines tokens. @plugin still exists to load JavaScript plugins, including the official typography and forms plugins. The hub is tailwind.

Load official plugins with @plugin

Install the package, then declare it after the import.

@import "tailwindcss";
@plugin "@tailwindcss/typography";
@plugin "@tailwindcss/forms";
  • Typography adds prose for HTML you do not control (Markdown, CMS output). Use dark:prose-invert for dark mode, max-w-none to remove the built-in max width, and not-prose to opt a subtree out.
  • Forms resets form controls to a baseline that utilities can override.

Customize prose colors by defining a theme as a utility:

@utility prose-brand {
  --tw-prose-body: var(--color-ink);
  --tw-prose-headings: var(--color-ink);
  --tw-prose-links: var(--color-brand);
}

Then write class="prose prose-brand".

Define custom utilities with @utility

Use @utility, not @layer utilities, so the class works with variants such as hover: and lg:.

@utility scrollbar-hidden {
  scrollbar-width: none;
  &::-webkit-scrollbar {
    display: none;
  }
}
 
@utility tab-* {
  tab-size: --value(--tab-size-*);
}

The second form is a functional utility that reads theme values. Keep multi-rule component classes in @layer components.

Define custom variants with @custom-variant

@custom-variant hocus (&:is(:hover, :focus-visible));
@custom-variant theme-midnight (&:where([data-theme="midnight"] *));

hocus:text-brand then applies on hover or keyboard focus. Variants such as rtl: and print: already exist; do not redefine them.

Share extensions as CSS

Put @theme, @utility, and @custom-variant blocks in a CSS file and import it from each project: @import "../brand/theme.css";. Use @plugin only for packages that need JavaScript.

Skip plugins that v4 made redundant

  • Container queries (@container, @md:) are built in; see tailwind-responsive. Do not install @tailwindcss/container-queries.
  • line-clamp-* and aspect-* are core utilities; the separate line-clamp and aspect-ratio plugins are unnecessary.
  • theme(spacing.12) is deprecated; use theme variables or --spacing(12).

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