/design-systems-slds-apply

name: design-systems-slds-apply
description: "Apply SLDS-compliant UI using the correct blueprints, styling hooks, utility classes, and icons. Use when building any UI that needs SLDS, choosing between Lightning Base Components and SLDS Blueprints, applying styling hooks for theming, using utility classes for layout and spacing, or selecting icons. Triggers include \"build a modal\", \"create a form\", \"data table\", \"SLDS styling\", \"style with hooks\", \"add an icon\"."
metadata:
  version: "1.1"
  domains: ["Design Systems"]
  relatedSkills:
    - "design-systems-slds-validate"
  cliTools:
    - tool: ["npx"]
      semver: ">=7.0.0"
    - tool: ["node"]
      semver: ">=18.0.0"

Applying SLDS

The **Salesforce Lightning Design System (SLDS)** is a CSS framework with thousands of artifacts. This skill teaches agents how to find and correctly use them.

> **Version:** This skill targets **SLDS v2**. Legacy `--lwc-*` tokens and `slds-*--modifier` syntax are deprecated. > > **Audit scope:** The companion `design-systems-slds-validate` skill analyzer only scans `.css`, `.html`, and `.js` files. Use it directly for LWC and similar HTML/CSS/JS components; treat it as a partial signal for JSX/TSX or other framework-specific template formats and supplement with manual review.

What is SLDS?

| Artifact | Count | Description | |----------|-------|-------------| | **Lightning Base Components** | ~70 | Pre-built LWC components (LWC only) | | **SLDS Blueprints** | 85 | CSS/HTML patterns for any framework | | **Styling Hooks** | 523 | CSS custom properties (`--slds-g-*`) for theming | | **Utility Classes** | 1,147 | Rapid styling classes for spacing, layout, visibility | | **Icons** | 1,732 | SVG icons across 5 categories |

---

Scope

**This skill covers:**

• Which blueprint to use for a given UI pattern
• How to style with hooks (color, spacing, typography, shadows, borders)
• Which utility classes to use for layout, spacing, visibility
• Which icon to use and from which category
• SLDS naming conventions, class structure, hook syntax

**This skill includes basic accessibility reminders** (icon alt text, focus outlines, color-not-sole-indicator) in the validation checklists. Full WCAG compliance requires a dedicated accessibility review.

**This skill does NOT cover (use companion skills):**

• **Design decisions** -- visual hierarchy, composition, interaction patterns
• **LWC mechanics** -- component structure, @wire, @api, lifecycle, events (not yet available)
• **Full accessibility** -- WCAG conformance, ARIA patterns, keyboard navigation, focus management, contrast ratios (not yet available)

---

Component Selection Hierarchy

Always follow this order:

1. Lightning Base Components (LWC only)    ← Check first
2. SLDS Blueprints (any framework)         ← Use exact SLDS classes
3. Custom with Styling Hooks               ← Use var(--slds-g-*)
4. Custom CSS (last resort)                ← Still use hooks for values

If building in LWC, check for an LBC first: [Lightning Component Library](https://developer.salesforce.com/docs/component-library/overview/components)

If no LBC exists (or not using LWC), select an SLDS Blueprint. See [references/component-selection.md](references/component-selection.md).

---

Core Rules

Do

• Follow the selection hierarchy: LBC > Blueprint > Hooks > Custom CSS
• Use `var(--slds-g-*, fallback)` for all themeable values
• Create custom classes (`my-*`, `c-*`) instead of overriding `.slds-*`
• **Verify every hook, class, and utility exists before using it** — run the search scripts; never assume an artifact exists based on naming patterns (see [Verify Before You Use](#verify-before-you-use))
• Pair surface colors with on-surface colors for text
• Provide `alternative-text` on every `<lightning-icon>`

Don't

• Hard-code colors, spacing, or typography values
• Override `.slds-*` classes directly
• Use deprecated `--lwc-*` tokens as primary values
• Use `--slds-s-*` (shared) hooks -- they are private/internal
• Reassign hook values -- only reference them with `var()`
• Use color alone to convey meaning
• Invent hook names by interpolating patterns from other families (see Naming Traps below)

---

Hook Naming Traps

SLDS hook families do NOT all follow the same naming pattern. Agents frequently invent hooks that don't exist by assuming `{prefix}-{number}` works universally. **Always verify a hook exists** via the bundled `search-hooks.cjs` script or `assets/hooks-index.json` before using it.

Trap 1: Font size hooks are NOT numbered

| Wrong (does not exist) | Correct | Notes | |------------------------|---------|-------| | `--slds-g-font-size-3` | `--slds-g-font-scale-1` | Font sizes use `font-scale-*`, not `font-size-*` | | `--slds-g-font-size-4` | `--slds-g-font-scale-2` | Only `--slds-g-font-size-base` exists (base size) | | `--slds-g-font-size-8` | `--slds-g-font-scale-6` | Scale goes: neg-4 through 10 |

**Rule:** For font sizes, use `--slds-g-font-size-base` (the one base size) or `--slds-g-font-scale-*` (the numbered scale). Never `--slds-g-font-size-N`.

Trap 2: Color hooks always require a number

| Wrong (does not exist) | Correct | Notes | |------------------------|---------|-------| | `--slds-g-color-on-surface` | `--slds-g-color-on-surface-2` | All color hooks need a number | | `--slds-g-color-on-accent` | `--slds-g-color-on-accent-1` | Pick 1/2/3 by emphasis level | | `--slds-g-color-surface` | `--slds-g-color-surface-1` | No unnumbered base form |

**Rule:** Every `--slds-g-color-*` hook ends in a number. Pick by emphasis: `-1` (low), `-2` (medium), `-3` (high).

Trap 3: Not all values have hook equivalents

Some CSS values (e.g., `min-width: 7rem` for label alignment) have no SLDS hook. This is acceptable:

.c-field-label {
  /* No SLDS hook exists for this width; intentional custom value */
  min-width: 7rem;
}

**Rule:** When no hook exists, use the value directly with a comment e