sgds-utilities - SKILL.md Agent Skill

name: "sgds-utilities" description: "Complete reference for all SGDS utility classes with the sgds: prefix. Use when users ask about setup, background-color, text-color, border-color, border-width, border-radius, typography, spacing, grid, dimension, opacity, color-semantics, or any sgds: Tailwind utility class. Also covers Tailwind v4 imports, theme switching, and framework integration for utilities." metadata: author: singapore-design-system version: "0.0.0" audience: external category: utilities

SGDS Utilities

The Utilities API — a set of atomic classes powered by Tailwind v4, scoped under the sgds: prefix. Developers apply SGDS design decisions directly in markup using this syntax rather than writing custom CSS.

Core Concept: sgds: Prefix

All SGDS utility classes use the sgds: prefix (Tailwind v4 @theme syntax):

<!-- ✅ Correct -->
<div class="sgds:p-4 sgds:bg-primary-default sgds:text-white">Content</div>

<!-- ❌ Wrong - missing prefix -->
<div class="p-4 bg-primary-default text-white">Content</div>

Required Setup

Import Utility CSS

utility.css is a Tailwind source file — it contains Tailwind v4 directives (@theme, @import "tailwindcss/theme.css") that must be processed by Tailwind's build pipeline. It cannot be imported directly in JavaScript.

Import it inside your project's main CSS file (the one Tailwind processes):

/* e.g. globals.css, index.css, main.css */
@import "@govtechsg/sgds-web-component/css/utility.css";

Tailwind will resolve and process the nested imports at build time, generating all sgds: utility classes.

Without this import, utility classes will not work.

Optional: Theme Setup

For theme-aware utilities that adapt to light/dark mode (background colors, text colors, border colors), import the theme files in your project's CSS file:

/* e.g. globals.css, index.css, main.css */
@import "@govtechsg/sgds-web-component/themes/day.css";
@import "@govtechsg/sgds-web-component/themes/night.css";

When Theme Setup is Required

Import theme files when using:

Background colors: sgds:bg-surface-default, sgds:bg-primary-default, etc.
Text colors: sgds:text-default, sgds:text-primary-default, etc.
Border colors: sgds:border-default, sgds:border-primary-default, etc.

When Theme Setup is Optional

Theme files are NOT required for:

Spacing: sgds:p-4, sgds:m-2, sgds:gap-6
Typography sizing: sgds:text-xl, sgds:font-bold
Border radius: sgds:rounded-lg
Opacity: sgds:opacity-50
Layout: sgds:flex, sgds:grid

Theme Switching

To toggle between light and dark themes programmatically:

<button id="theme-toggle">Toggle Theme</button>

<script>
  const toggleButton = document.getElementById("theme-toggle");
  toggleButton.addEventListener("click", () => {
    document.documentElement.classList.toggle("sgds-theme-night");
  });
</script>

Classes with theme-aware tokens automatically update when the theme changes.

Verification

Test that setup is complete:

<!DOCTYPE html>
<html>
  <head>
    <!-- processed by your Tailwind build -->
  </head>
  <body class="sgds:bg-default sgds:p-6">
    <div class="sgds:bg-surface-raised sgds:p-4 sgds:rounded-lg">
      <h1 class="sgds:text-heading-default sgds:text-2-xl sgds:font-bold sgds:mb-4">Setup Test</h1>
      <p class="sgds:text-body-default sgds:mb-4">If this text is styled correctly, your setup is complete.</p>
      <button
        class="sgds:bg-primary-default sgds:text-white sgds:px-4 sgds:py-2 sgds:rounded"
        onclick="document.documentElement.classList.toggle('sgds-theme-night')"
      >
        Toggle Theme
      </button>
    </div>
  </body>
</html>

Framework-Specific Setup

Since SGDS utilities are built on Tailwind v4, you must first set up Tailwind CSS for your framework before importing the SGDS CSS files.

Step 1: Follow the Tailwind CSS guide for your framework:

Framework	Guide
Next.js	https://tailwindcss.com/docs/installation/framework-guides/nextjs
Nuxt (Vue)	https://tailwindcss.com/docs/installation/framework-guides/nuxt
Angular	https://tailwindcss.com/docs/installation/framework-guides/angular
SvelteKit	https://tailwindcss.com/docs/installation/framework-guides/sveltekit
Astro	https://tailwindcss.com/docs/installation/framework-guides/astro
Gatsby	https://tailwindcss.com/docs/installation/framework-guides/gatsby
React Router	https://tailwindcss.com/docs/installation/framework-guides/react-router
Vite (generic)	https://tailwindcss.com/docs/installation/using-vite

Not listed? See the full list at https://tailwindcss.com/docs/installation/framework-guides.

Step 2: After Tailwind is set up, add the SGDS @import to the same CSS file that Tailwind processes (usually globals.css, main.css, or index.css):

@import "@govtechsg/sgds-web-component/css/utility.css";

/* Optional: theme-aware color tokens */
@import "@govtechsg/sgds-web-component/themes/day.css";
@import "@govtechsg/sgds-web-component/themes/night.css";

Available Utilities

Category	Utility	Theme files required	Reference
Layout	Grid system (`.sgds-container`, `.sgds-grid`, `.sgds-col-*`)	No	→ reference/grid.md
Layout	Container dimensions (`sgds:w-container`, `sgds:max-w-container-*`)	No	→ reference/dimension.md
Spacing	Margin, padding, gap (`sgds:p-`, `sgds:m-`, `sgds:gap-*`, semantic tokens)	No	→ reference/spacing.md
Color	Color token suffix semantics (default, emphasis, muted, fixed, etc.)	—	→ reference/color-semantics.md
Color	Background colors (`sgds:bg-*`)	Yes	→ reference/background-color.md
Color	Text colors (`sgds:text-*`)	Yes	→ reference/text-color.md
Color	Border colors (`sgds:border-*` color)	Yes	→ reference/border-color.md
Border	Border width and sides (`sgds:border`, `sgds:border-2`, `sgds:border-l-4`, etc.)	No	→ reference/border-width.md
Border	Border radius (`sgds:rounded-`, `sgds:rounded-form-`)	No	→ reference/border-radius.md
Typography	Font size, weight, line height, letter spacing, font family	No	→ reference/typography.md
Visual	Opacity (`sgds:opacity-*`)	No	→ reference/opacity.md
Visual	Elevation / box shadows (`sgds:shadow-`, `sgds:shadow-edge-`)	No	→ reference/elevation.md
Responsive	Breakpoint prefixes (`sgds:xs:`, `sgds:sm:`, `sgds:md:`, `sgds:lg:`, `sgds:xl:`, `sgds:2-xl:`)	No	→ reference/breakpoint.md
Patterns	Cross-category component patterns (card, alert, form, modal)	—	→ reference/overview-patterns.md

Quick Reference by Use Case

Page layout, columns, responsive grid → reference/grid.md Container width, max-width → reference/dimension.md Spacing between sections, components, text → reference/spacing.md Color token suffixes (default, emphasis, muted, etc.) → reference/color-semantics.md Card backgrounds, surface colors → reference/background-color.md Text content colors → reference/text-color.md Borders and rounded corners → reference/border-color.md, reference/border-width.md, reference/border-radius.md Headings, body text, font sizes → reference/typography.md Transparent overlays, disabled states → reference/opacity.md Card shadows, modal depth, sticky header/footer edges → reference/elevation.md Responsive breakpoints, show/hide at viewport sizes → reference/breakpoint.md

For AI Agents:

Always verify users have completed setup (utility CSS import) before suggesting utility classes.
Theme files (day.css, night.css) are only needed for color utilities (background, text, border colors) — not for spacing, typography, border radius, or opacity.
When users ask about a specific utility category, read the corresponding reference file before generating output.
The grid system (.sgds-container, .sgds-grid, .sgds-col-*) is always preferred over generic Tailwind sgds:grid-cols-* — see reference/grid.md.
Prefer semantic spacing utilities (sgds:gap-layout-*, sgds:p-component-*) over raw numeric utilities (sgds:p-4, sgds:gap-6) — they are responsive and encode design intent.
Prefer semantic font-size utilities (sgds:text-display-*, sgds:text-heading-*, sgds:text-body-*) over raw scale utilities — they are responsive.
Color suffix modifiers (default, emphasis, muted, surface, fixed-light, fixed-dark, inverse) are shared across all color utilities — see reference/color-semantics.md.
Never use inline style attributes. If a layout or visual property is needed, find the equivalent sgds: utility class. If no utility class exists for the exact value, prefer the closest semantic utility. Only resort to a CSS custom property override as a last option, and never via a style attribute.
Never use raw sgds:max-w-* utilities for container sizing. Raw classes like sgds:max-w-2xl, sgds:max-w-lg, sgds:max-w-sm map to small Tailwind numeric values and are not part of the SGDS design system. Use sgds:max-w-container-* (md/lg/xl/2-xl/3-xl) for inner containers, or sgds:w-container for the top-level page wrapper. See reference/dimension.md.