sfcc-sfra-scss— agent skill

SFRA SCSS Best Practices (AI-Agent Optimized)

Purpose: Provide a concise, implementation‑ready reference for styling and theming Salesforce B2C Commerce SFRA storefronts using SCSS. Optimized for automated reasoning, safe overrides, upgrade resilience, and performant output.

1. Core Principles (Never Skip)

Red flag triggers for re‑evaluation: deep nesting (>3), repeated hardcoded colors, !important, duplicated breakpoint literals, editing compiled CSS, or missing initial @import.

AI Guardrail (fast reject): If asked to "change base SCSS" directly, respond with an override strategy instead of editing base source.

2. Minimal Override Workflow (Algorithm)

1. Inspect element in browser → capture compiled CSS filename (e.g. product/detail.css) & selector(s).
2. Locate source in base: app_storefront_base/cartridge/client/default/scss/<path>.scss.
3. Recreate identical relative path in custom cartridge under cartridge/client/default/scss/.
4. Add header: @import '~base/<path>'; (must be line 1; no preceding BOM/comment).
5. Append scoped overrides (BEM, tokens, mixins only—no raw hex unless introducing new token).
6. Run npm run compile:scss (or project alias) → deploy → verify cascade diff.
7. If change is global (color, spacing, radius) prefer variable override in _variables.scss before component override.

Decision Tree:

Plugin Extension Nuances (Observed from plugin_wishlists):

• Keep plugin additions minimal: import base global first inside plugin global.scss (@import "~base/global";) then only plugin-specific partials.
• Do NOT re-import variables inside multiple plugin partials unless you need local compilation context—prefer central import in the entry file to avoid duplication.
• Avoid redefining spacing tokens mid-file (e.g. $spacer inside a feature file) unless intentionally creating a component-scoped token; document with a comment // local token.
• Consolidate repeated keyframes: If multiple alerts use identical fade animation, define it once in a shared partial (e.g. components/_animations.scss) instead of inline per component.
• When plugin needs base mixins (e.g. Bootstrap breakpoints) prefer @import "~base/global"; rather than directly importing bootstrap again to reduce risk of version drift.

3. Canonical SCSS Directory (7‑1 Adapted)

scss/
  abstracts/  (_variables.scss, _mixins.scss, _functions.scss)
  base/       (_reset.scss, _typography.scss, _base.scss)
  layout/     (_header.scss, _footer.scss, _navigation.scss, _grid.scss)
  components/ (_buttons.scss, _product-tile.scss, _carousel.scss, ...)
  pages/      (_home.scss, _checkout.scss, _pdp.scss, ...)
  vendors/    (_bootstrap-overrides.scss, _plugin-X.scss)
  global.scss  (imports only – no rules)

Import Order (global.scss):

1. abstracts (variables → mixins → functions)
2. vendors
3. base
4. layout
5. components
6. pages

SFRA Reality Snapshot: The core global.scss in app_storefront_base imports: variables, skin/skinVariables, bootstrap custom, overrides, utilities, icon libraries, then individual component partials. AI agents should treat this as the authoritative ordering when composing custom global.scss overlays: always import base global first in plugin/global contexts, then plugin additions.

Rule: No CSS selectors in global.scss; only @import.

4. Naming & Specificity Strategy (BEM + SFRA Conventions)

Guidelines:

• Avoid HTML element chaining: prefer .mini-cart__count not header .mini-cart span.count.
• Never exceed 3 levels of specificity (block + element + modifier/state).
• Do not style IDs; reserve for scripting anchor only if necessary.
• Existing SFRA partials sometimes nest deeper (e.g. .product-tile .tile-body .price .tiered .value). When extending these, do NOT replicate entire nesting; extract just the block root with a modifier class you control (e.g. .product-tile--compact).
• For legacy classes not following BEM (e.g. .wishlistTile), retain original naming but annotate exception with justification comment to aid future refactor and silence lint selectively—in code: /* stylelint-disable-line */.

5. Token & Theme Management

Override pattern (abstracts/_variables.scss):

@import '~base/variables'; // must stay first
// Theme – Colors
$primary: #0B5FFF; // Brand blue
$secondary: #00A676;
$body-bg: #F8F9FA;
$body-color: #212529;
// Typography
$font-family-sans-serif: 'Inter', 'Helvetica Neue', Arial, sans-serif;
$font-family-serif: 'Merriweather', Georgia, serif;
// Radii / Spacing
$border-radius: 2px;
$btn-padding-y: 0.5rem;
$btn-padding-x: 1.125rem;

Rules:

• Only override variables you intentionally change.
• Introduce new tokens with consistent naming ($color-*, $space-*, $z-*).
• Never redefine variables in component partials—centralize.
• If a plugin must create a small local scalar (e.g. $spacer for a one-off layout tweak), prefix with component context when possible ($wishlist-spacer) to avoid collision with global tokens.
• Avoid re-importing base variables in each partial—imports are concatenated; repeated imports increase compile time and risk inconsistent overrides if order diverges.

6. Reuse Mechanisms (Decision Matrix)

Responsive Mixin:

$breakpoints: (
  sm: 576px,
  md: 768px,
  lg: 992px,
  xl: 1200px
) !default;

@mixin mq($bp) {
  @if map-has-key($breakpoints, $bp) {
    @media (min-width: map-get($breakpoints, $bp)) { @content; }
  } @else { @warn 'Unknown breakpoint: #{$bp}'; }
}

Usage:

.product-tile { width: 100%; @include mq(md) { width: 50%; } }

Bootstrap Breakpoints Interop: SFRA base uses Bootstrap's media-breakpoint-* mixins. When generating code referencing base breakpoints, prefer those existing mixins (@include media-breakpoint-down(md) { ... }) if the base already depends on Bootstrap, instead of introducing a parallel custom map to avoid divergence. Use the custom $breakpoints + mq() pattern only if project intentionally decouples from Bootstrap.

7. Example Override (PDP Title)

File: product/detail.scss

@import '~base/product/detail'; // inherit base

.product-detail__name {
  font-family: $font-family-serif;
  font-size: 2.4rem;
  color: $primary;
}

Compiled file resolved via assets.addCss('/css/product/detail.css') with cartridge path precedence—no ISML changes needed. AI Validation Step: After generation, assert snippet begins with base import and contains only new selectors or modified declarations—no duplication of entire base blocks.

8. Component Patterns Library (Sample Snippets)

Buttons (components/_buttons.scss):

@import '~base/components/buttons';

.btn--pill { border-radius: 999rem; }
.btn--outline-secondary {
  color: $secondary; background: transparent; border: 1px solid $secondary;
  &:hover { background: $secondary; color: #fff; }
}

Product Tile (components/_product-tile.scss):

@import '~base/components/product-tile';

.product-tile {
  border: 1px solid transparent; transition: box-shadow .2s;
  &:hover { box-shadow: 0 4px 12px rgba(0,0,0,.1); border-color: $gray-300; }
  &__price--sale { color: $danger; font-weight: 600; }
}

Refactor Tip: Instead of deeply nested overrides inside `.product-tile .tile-body .price .tiered .value`, target a purposeful modifier class (`.product-tile__price--tiered-value`) you add in ISML for long-term maintainability.

Checkout (pages/_checkout.scss):

@import '~base/pages/checkout';
.checkout-nav .nav-link { background:$gray-200; color:$gray-600;
  &.active { background:$primary; color:#fff; }
}

9. Responsive Strategy

Anti‑Pattern: Desktop CSS first + mobile overrides via @media (max-width) – leads to override churn. Plugin Reality: Wishlist plugin currently mixes media-breakpoint-up and media-breakpoint-down usage; maintain consistency—choose mobile-first pattern (prefer -up for enhancements) and refactor legacy -down only when safe.

10. Accessibility & Inclusive Styling

Utility Example:

.u-visually-hidden { position:absolute!important; width:1px; height:1px; padding:0; margin:-1px; overflow:hidden; clip:rect(0 0 0 0); white-space:nowrap; border:0; }

Animation Respect: Provide a reduced-motion alternative when introducing keyframe animations (e.g. fading alerts). Centralize keyframes and wrap any large movement inside @media (prefers-reduced-motion: no-preference); fallback: immediate end state.

11. Performance Practices

Suggested CI Budget: Global CSS ≤ 250KB uncompressed (enterprise baseline) – fail build if regression > +15% week‑over‑week. Duplicate Import Scan: Add a CI grep step to detect repeated @import "~base/variables"; inside plugin component partials—emit warning to consolidate.

12. Linting & Quality Automation

Install:

npm i -D stylelint stylelint-config-standard-scss stylelint-declaration-strict-value

Config (.stylelintrc.json):

{
  "extends": "stylelint-config-standard-scss",
  "plugins": ["stylelint-declaration-strict-value"],
  "rules": {
    "selector-class-pattern": ["^([a-z][a-z0-9]*)(__(?:[a-z0-9]+))?(--[a-z0-9-]+)?$", {"message": "Use BEM: block__element--modifier"}],
    "max-nesting-depth": 2,
    "declaration-no-important": true,
    "scale-unlimited/declaration-strict-value": [["color", "background-color", "border-color", "font-size"], {"ignoreValues": ["inherit", "transparent", "currentColor"]}]
  }
}

Script:

"scripts": { "lint:scss": "stylelint 'cartridges/**/*.scss' --cache" }

Optional: pre‑commit hook with Husky + lint-staged.

AI Generation Rule Set: When asked to produce SCSS:

1. Always start with required base import (unless file is abstracts/_variables.scss).
2. Do not inline raw colors already expressible as existing tokens—prefer token reference.
3. Replace any suggested !important with a cascade adjustment strategy comment.
4. Provide at most one new local token; advise moving to global if reused >2 times.
5. Add a 2-line header comment with PURPOSE + SAFE REMOVE classification.

13. Anti‑Patterns (Refactor Immediately)

14. Troubleshooting Matrix

15. Promptable Action Snippets (For AI Agents)

16. Migration Checklist (Before Deploy)

[] All overrides start with base import [] No direct edits to app_storefront_base [] Variables overridden centrally only [] Lint passes (no warnings in CI) [] No !important (or justified + documented) [] CSS bundle size budget respected [] Critical CSS updated for homepage + PDP [] Source maps disabled for production [] New utilities documented (inline comment header) [] No duplicate keyframe blocks with identical declarations [] Plugin global includes base global exactly once

17. Reference Quick Commands

# Compile SCSS
npm run compile:scss

# Lint SCSS
npm run lint:scss

# Find hardcoded colors (non-variable)
// in app_custom/cartridge/client/default/scss/abstracts/_variables.scss

# Estimate partial usage (appearance in compiled)
@import '~base/variables';

CI Grep Helpers (Optional):

grep -R "@import \"~base/variables\"" cartridges/plugin_* | sort
grep -R "@keyframes fade" cartridges/ | wc -l

18. Secure & Maintainable Patterns

Header Annotation Block (optional for generated partial):

// PURPOSE: Override of base product tile for brand visual refinement
// DEPENDS: ~base/components/product-tile
// SAFE REMOVE: Yes (reverts to base visual style)

Classification Legend:

• SAFE REMOVE: Removing file reverts to acceptable base styling.
• CONDITIONAL: Removal affects brand contract (document impact).
• CRITICAL: Provides accessibility or functional styling (never remove without replacement).

19. When NOT to Override

20. AI Generation Quick Checklist (Inline in Responses)

Provide along with any generated SCSS so humans can validate rapidly:

1. Base Import Present? (Yes/No)
2. Variable Overrides? (List or None)
3. New Tokens Introduced? (List or None)
4. Max Nesting Depth (#)
5. Uses Existing Breakpoint Mixins? (Yes/No)
6. Any Raw Hex Values? (List or None + justification)
7. Keyframes Added? (Name or None; already exists?)
8. Accessibility Considerations? (Focus/contrast/motion)
9. Removable Classification (SAFE REMOVE / CONDITIONAL / CRITICAL)
10. Lint‑Sensitive Areas (Exceptions with reason)

If any answer violates a stated rule, propose an auto-correction diff, not just a warning.