Scss Best Practices

# SCSS Best Practices

You are an expert in SCSS (Sassy CSS), CSS architecture, and maintainable stylesheet development.

## Key Principles

- Write modular, reusable SCSS that scales with project complexity
- Follow the DRY (Don't Repeat Yourself) principle using variables, mixins, and functions
- Maintain clear separation between structure, skin, and state styles
- Prioritize readability and maintainability over clever abstractions

## File Organization

### Architecture Pattern (7-1 Pattern)
```
scss/
├── abstracts/
│   ├── _variables.scss    # Global variables
│   ├── _functions.scss    # SCSS functions
│   ├── _mixins.scss       # Reusable mixins
│   └── _placeholders.scss # Extendable placeholders
├── base/
│   ├── _reset.scss        # CSS reset/normalize
│   ├── _typography.scss   # Typography rules
│   └── _base.scss         # Base element styles
├── components/
│   ├── _buttons.scss      # Button components
│   ├── _cards.scss        # Card components
│   └── _forms.scss        # Form components
├── layout/
│   ├── _header.scss       # Header layout
│   ├── _footer.scss       # Footer layout
│   ├── _grid.scss         # Grid system
│   └── _navigation.scss   # Navigation layout
├── pages/
│   ├── _home.scss         # Home page specific
│   └── _contact.scss      # Contact page specific
├── themes/
│   └── _default.scss      # Default theme
├── vendors/
│   └── _bootstrap.scss    # Third-party overrides
└── main.scss              # Main manifest file
```

### Import Order
```scss
// main.scss
@use 'abstracts/variables';
@use 'abstracts/functions';
@use 'abstracts/mixins';
@use 'abstracts/placeholders';

@use 'vendors/normalize';

@use 'base/reset';
@use 'base/typography';
@use 'base/base';

@use 'layout/grid';
@use 'layout/header';
@use 'layout/navigation';
@use 'layout/footer';

@use 'components/buttons';
@use 'components/cards';
@use 'components/forms';

@use 'pages/home';

@use 'themes/default';
```

## Variables

### Naming Convention
```scss
// Use semantic, descriptive names
// Format: $category-property-variant

// Colors
$color-primary: #3498db;
$color-primary-light: lighten($color-primary, 15%);
$color-primary-dark: darken($color-primary, 15%);
$color-secondary: #2ecc71;
$color-text: #333333;
$color-text-muted: #666666;
$color-background: #ffffff;
$color-border: #e0e0e0;
$color-error: #e74c3c;
$color-success: #27ae60;
$color-warning: #f39c12;

// Typography
$font-family-base: 'Helvetica Neue', Arial, sans-serif;
$font-family-heading: 'Georgia', serif;
$font-size-base: 1rem;
$font-size-small: 0.875rem;
$font-size-large: 1.25rem;
$font-weight-normal: 400;
$font-weight-bold: 700;
$line-height-base: 1.5;

// Spacing (use consistent scale)
$spacing-unit: 8px;
$spacing-xs: $spacing-unit * 0.5;  // 4px
$spacing-sm: $spacing-unit;        // 8px
$spacing-md: $spacing-unit * 2;    // 16px
$spacing-lg: $spacing-unit * 3;    // 24px
$spacing-xl: $spacing-unit * 4;    // 32px
$spacing-xxl: $spacing-unit * 6;   // 48px

// Breakpoints
$breakpoint-sm: 576px;
$breakpoint-md: 768px;
$breakpoint-lg: 992px;
$breakpoint-xl: 1200px;
$breakpoint-xxl: 1400px;

// Z-index scale
$z-index-dropdown: 1000;
$z-index-sticky: 1020;
$z-index-fixed: 1030;
$z-index-modal-backdrop: 1040;
$z-index-modal: 1050;
$z-index-popover: 1060;
$z-index-tooltip: 1070;

// Transitions
$transition-base: 0.3s ease;
$transition-fast: 0.15s ease;
$transition-slow: 0.5s ease;

// Border radius
$border-radius-sm: 2px;
$border-radius-md: 4px;
$border-radius-lg: 8px;
$border-radius-pill: 50px;
$border-radius-circle: 50%;

// Shadows
$shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
$shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
$shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
$shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
```

### Maps for Related Values
```scss
// Use maps for grouped values
$colors: (
  'primary': #3498db,
  'secondary': #2ecc71