Goal

Systematically migrate Lightning Web Components from SLDS 1 to SLDS 2 using the SLDS linter and structured guidance for fixing violations across all styling hook categories.

SLDS 2 Styling Hook Categories

Category	Hook Prefix	What It Replaces
Color	`--slds-g-color-*`	Hardcoded colors, `--lwc-color*` tokens
Spacing	`--slds-g-spacing-*`	Hardcoded margins, padding, gaps
Sizing	`--slds-g-sizing-*`	Hardcoded widths, heights, dimensions
Typography	`--slds-g-font-*`	Hardcoded font sizes, weights, line heights
Border/Radius	`--slds-g-radius-border-` , `--slds-g-sizing-border-`	Hardcoded border-radius, border-width
Shadow	`--slds-g-shadow-*`	Hardcoded box-shadow values

Color hooks require the most judgment (context-dependent selection). Non-color hooks are mostly numbered scales with straightforward mappings.

Prerequisites

Node.js 14.x or higher installed
Access to component CSS and markup files (
```
.html
```
for LWC,
```
.cmp
```
for Aura)
Terminal/command line access to run linter
Git repository for backup (recommended)

Workflow

1. Run SLDS linter with auto-fix -> Handles simple violations automatically
2. Review linter output -> Identify remaining manual fixes needed
3. Fix by violation type -> Use per-rule reference guides
4. Choose the right hook -> Context-first, inspect HTML before deciding
5. Validate -> Re-run linter and confirm zero errors

Step 1: Run SLDS Linter

bash

npx @salesforce-ux/slds-linter@latest lint --fix .

The linter analyzes all CSS and markup files (

.html

for LWC,

.cmp

for Aura), auto-fixes simple violations, and reports remaining issues requiring manual intervention.

Step 2: Analyze Linter Output

The linter reports violations in this format:

componentName.css
  15:3  warning  Overriding slds-button isn't supported. To differentiate SLDS and
                 custom classes, create a CSS class in your namespace.
                 Examples: myapp-input, myapp-button.                        slds/no-slds-class-overrides

  23:5  error    The '--lwc-colorBackground' design token is deprecated. Replace it with
                 the SLDS 2 styling hook and set the fallback to '--lwc-colorBackground'.
                 1. --slds-g-color-surface-2
                 2. --slds-g-color-surface-container-2                      slds/lwc-token-to-slds-hook

  30:8  warning  Consider replacing the #ffffff static value with an SLDS 2 styling hook
                 that has a similar value:
                 1. --slds-g-color-surface-1
                 2. --slds-g-color-surface-container-1
                 3. --slds-g-color-on-accent-1
                 4. --slds-g-color-on-accent-2
                 5. --slds-g-color-on-accent-3                              slds/no-hardcoded-values-slds2

  31:15  error   Consider removing t(fontSizeMedium) or replacing it with
                 var(--slds-g-font-size-base, var(--lwc-fontSizeMedium, 0.8125rem)).
                 Set the fallback to t(fontSizeMedium). For more info, see
                 Styling Hooks on lightningdesignsystem.com.               slds/no-deprecated-tokens-slds1

Four violation types, each with its own fix approach (see Step 3).

Important: The linter flags all hardcoded values. Fix color, spacing, sizing, typography, border, and shadow values — but skip layout values (

100%

auto

inherit

none

). See rule-no-hardcoded-values.md for the full fix-vs-skip triage table.

Step 3: Fix Violations by Type

Each rule has a dedicated reference guide with full examples and decision logic:

Violation Rule	Quick Summary	Reference
`slds/no-hardcoded-values-slds2`	Replace hardcoded values with SLDS hook + original as fallback	rule-no-hardcoded-values.md
`slds/lwc-token-to-slds-hook`	Replace `--lwc-*` tokens with SLDS 2 hook, keep LWC token as fallback	rule-lwc-token-to-slds-hook.md
`slds/no-slds-class-overrides`	Create component-prefixed class, add to markup alongside SLDS class	rule-no-slds-class-overrides.md
`slds/no-deprecated-tokens-slds1`	Replace legacy `t()` / `token()` syntax with SLDS 2 hook + LWC fallback	rule-no-deprecated-tokens-slds1.md

Always include fallback values —

var(--slds-g-hook, originalValue)

where

originalValue

is the exact original from the source CSS.

Class Override Quick Reference

Class overrides require changes to both CSS and markup (

.html

.cmp

). This is the most commonly missed step:

CSS: Rename

.slds-*

selector →

{componentName}-{sldsElementPart}

(camelCase)

Markup: Add the new class alongside the SLDS class — never remove the SLDS class

css

/* Before */ .slds-button { border-radius: 8px; }
/* After */  .myComponent-button { border-radius: 8px; }

html

<!-- Markup: both classes --> <button class="slds-button myComponent-button">Click</button>

See rule-no-slds-class-overrides.md for descendant selectors, multi-class selectors, and naming conventions.

Step 4: Choose the Right Hook

Color hooks require context-based selection — inspect the HTML to determine the element's role before choosing a hook family. See color-hooks-decision-guide.md for decision trees, all 5 hook families, and background-foreground pairing rules.

Non-color hooks are simpler — match the CSS value to the numbered scale. See non-color-hooks-decision-guide.md for value-to-hook lookup tables covering spacing, sizing, typography, borders, radius, and shadows.

Step 5: Validate and Verify

Linter feedback loop — repeat until zero errors:

1. npx @salesforce-ux/slds-linter@latest lint .
2. Review errors -> fix by type (Step 3)
3. Re-run linter
4. Repeat until output shows: 0 errors

Validation

No
```
.slds-*
```
classes in CSS selectors
No
```
var(--lwc-*)
```
tokens without SLDS 2 replacements
All hooks include fallback values
Background/foreground color hooks from same family
Original SLDS classes preserved in HTML
Spacing uses numbered hooks (not named like
```
spacing-medium
```
)
Typography uses numbered hooks (not named like
```
font-weight-bold
```
)
Component renders correctly in light/dark mode and density settings

See migration-checklist.md for the full validation checklist.

Output

Return the fully migrated CSS (and updated HTML markup where class overrides were fixed) with zero SLDS linter violations. All styling hooks must include fallback values preserving the original CSS values.

Advanced Patterns

Color-Mix for Transparency

When a hardcoded value uses

rgba()

or transparency, use

color-mix()

with the SLDS hook to preserve opacity:

css

/* Before */
border-color: rgba(186, 5, 23, 0.7);

/* After — use oklab color space for perceptual consistency */
border-color: color-mix(in oklab, var(--slds-g-color-palette-red-40, rgb(181,54,45)), transparent 30%);

Formula: To achieve X% opacity, use

(100 - X)%

transparent in

color-mix

70% opacity →
```
transparent 30%
```
50% opacity →
```
transparent 50%
```

Use opaque

rgb()

as fallback (not

rgba()

) —

color-mix

handles the transparency.

calc() Expressions with Tokens

When migrating

t('calc(...)')

calc()

with deprecated tokens:

css

/* Before — Aura t() with calc */
height: t('calc(' + lineHeightButton + ' + 2px)');

/* After — if calc is still needed */
height: calc(var(--lwc-lineHeightButton) + 2px);

/* After — if calc was unnecessary, simplify */
height: var(--lwc-lineHeightButton);

For

calc()

with

--lwc-*

tokens being replaced:

css

/* Before */
padding: calc(var(--lwc-spacingMedium) + 4px);

/* After */
padding: calc(var(--slds-g-spacing-4, var(--lwc-spacingMedium)) + 4px);

Tip: Often the

calc()

is unnecessary and can be simplified. Check if the result matches an existing hook value.

Key Constraints

Never invent hook names — only use hooks documented in the SLDS design system
Always include fallback values — the fallback must be the exact original value from the source CSS
Never change hardcoded numerical values — values like
```
100%
```
,
```
50%
```
,
```
200px
```
,
```
1.5
```
,
```
auto
```
,
```
0
```
,
```
inherit
```
,
```
none
```
,
```
flex: 1
```
are structural/layout values. Do not replace them with hooks and do not remove them — they are not styling hook candidates
No exact match? Leave as-is — if a hardcoded value doesn't closely correspond to any hook's rendered value, leave it unchanged rather than force-fitting
Match hook number to original value intensity — don't default to
```
-1
```
. Pick the variant closest to the original. See color-hooks-decision-guide.md
Only numbered scales — named hooks like
```
spacing-medium
```
,
```
font-weight-bold
```
,
```
radius-large
```
do NOT exist

Troubleshooting

Issue	Solution
Linter suggests 2+ color hook options	Inspect HTML context to determine element's semantic role — see color-hooks-decision-guide.md
Visual appearance changed after migration	Verify fallback values match originals; check surface vs container family
No hook available for hardcoded value	Leave unchanged; do not invent custom hook names
Linter says "Remove the static value" for `100%` , `auto` , etc.	Leave unchanged — these are layout values. Removing them breaks rendering.
CSS class naming errors	Use exact camelCase component name: `myComponent-button` , not `MyComponent-button`
Spacing/sizing doesn't match	Check value-to-hook mapping in non-color-hooks-decision-guide.md; verify spacing vs sizing usage
Named hook not working (e.g., `spacing-medium` )	Named hooks don't exist — use numbered scale: `spacing-4` for 16px, `font-weight-7` for inline bold emphasis (not headings)
Component looks different in compact density	Use density-aware hooks ( `--slds-g-spacing-var-*` ) for components that adapt to density

References

Color Hooks Decision Guide — All 5 color hook families, decision trees, background-foreground pairing, palette accessibility
Non-Color Hooks Decision Guide — Spacing, sizing, typography, borders, radius, and shadow hooks with lookup tables
Rule: No Hardcoded Values — Linter behavior, fix-vs-skip triage, replacement pattern, utility class workflow
Rule: LWC Token to SLDS Hook — Deprecated
```
--lwc-*
```
token replacement patterns
Rule: No Deprecated Tokens SLDS1 — Legacy
```
t()
```
/
```
token()
```
Aura syntax replacement patterns
Rule: No SLDS Class Overrides — Class renaming and HTML updates
Migration Examples — Before/after examples by scenario and complexity
Common Patterns — Classes never to override, deprecated SLDS 2 classes, palette fallbacks, tokens with no SLDS 2 equivalent
Migration Checklist — Full validation checklist

uplifting-components-to-slds2

NPX Install

Tags

SKILL.md Content