/* ==========================================================================
   Puzzle Engine - Shared Styles
   ========================================================================== */

/* --------------------------------------------------------------------------
   CSS Custom Properties (Variables)
   -------------------------------------------------------------------------- */
:root {
  /* Colors */
  --color-primary: #6b46c1;
  --color-primary-dark: #553c9a;
  --color-primary-light: #9f7aea;
  --color-secondary: #ed8936;
  --color-bg: #f7fafc;
  --color-bg-white: #ffffff;
  --color-text: #1a202c;
  --color-text-light: #4a5568;
  --color-text-muted: #718096;
  --color-border: #e2e8f0;
  --color-border-dark: #cbd5e0;
  --color-surface: #ffffff;
  --color-surface-hover: #f0f4f8;
  --color-success: #38a169;
  --color-warning: #d69e2e;
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  --font-mono: 'SF Mono', 'Consolas', 'Monaco', 'Menlo', monospace;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* Border Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  /* 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);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
}

/* --------------------------------------------------------------------------
   Reset & Base Styles
   -------------------------------------------------------------------------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.5;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* --------------------------------------------------------------------------
   Typography
   -------------------------------------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.25;
  color: var(--color-text);
}

h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }

p {
  margin-bottom: var(--spacing-md);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
}

/* --------------------------------------------------------------------------
   Layout Components
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.main-content {
  flex: 1;
  padding: var(--spacing-xl) 0;
}

/* --------------------------------------------------------------------------
   Header
   -------------------------------------------------------------------------- */
.header {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
  color: white;
  padding: var(--spacing-lg) 0;
  text-align: left;
}

.header .container {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.header__logo {
  margin: 0;
  flex-shrink: 0;
}

.header__logo-img {
  height: 80px;
  width: auto;
  vertical-align: middle;
}

.header__branding {
  flex: 1;
}

.header__title {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  margin: 0;
}

.header__tagline {
  font-size: var(--font-size-lg);
  opacity: 0.9;
  margin: var(--spacing-xs) 0 0 0;
}

.header__logo a {
  color: inherit;
  text-decoration: none;
}

/* --------------------------------------------------------------------------
   Header Navigation
   -------------------------------------------------------------------------- */
.header__nav {
  position: relative;
  margin-left: auto;
  display: flex;
  align-items: center;
}

.header__nav-toggle {
  background: none;
  border: none;
  font-size: 28px;
  color: white;
  cursor: pointer;
  padding: var(--spacing-sm);
  border-radius: var(--radius-sm);
  transition: background-color var(--transition-fast);
  line-height: 1;
}

.header__nav-toggle:hover {
  background-color: rgba(255, 255, 255, 0.2);
}

.header__nav-menu {
  position: absolute;
  top: 100%;
  right: 0;
  margin-top: 8px;
  min-width: 160px;
  background: var(--color-bg-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  display: none;
  flex-direction: column;
  padding: var(--spacing-xs) 0;
  z-index: 1000;
}

.header__nav-menu.is-visible {
  display: flex;
}

.header__nav-link {
  display: block;
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--color-text);
  font-size: var(--font-size-base);
  transition: background-color var(--transition-fast);
}

.header__nav-link:hover {
  background-color: var(--color-bg-alt);
  color: var(--color-primary);
}

.header__nav-link--active {
  color: var(--color-primary);
  font-weight: var(--font-weight-semibold);
  background-color: var(--color-bg-alt);
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */
.footer {
  background-color: var(--color-bg-white);
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-xl) 0;
  margin-top: auto;
}

.footer__content {
  text-align: center;
}

.footer__nav {
  display: flex;
  justify-content: center;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  flex-wrap: wrap;
}

.footer__nav a {
  color: var(--color-text-light);
  font-size: var(--font-size-sm);
}

.footer__nav a:hover {
  color: var(--color-primary);
}

.footer__license {
  background-color: var(--color-bg);
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  max-width: 600px;
  margin: 0 auto;
}

.footer__license-title {
  font-weight: 600;
  color: var(--color-success);
  margin-bottom: var(--spacing-xs);
  font-size: var(--font-size-sm);
}

.footer__license-text {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  margin: 0;
}

/* --------------------------------------------------------------------------
   Card Component
   -------------------------------------------------------------------------- */
.card {
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  transition: box-shadow var(--transition-base), transform var(--transition-base);
}

.card:hover {
  box-shadow: var(--shadow-lg);
}

.card--clickable:hover {
  transform: translateY(-2px);
}

.card__header {
  padding: var(--spacing-lg);
  border-bottom: 1px solid var(--color-border);
}

.card__body {
  padding: var(--spacing-lg);
}

.card__footer {
  padding: var(--spacing-md) var(--spacing-lg);
  background-color: var(--color-bg);
  border-top: 1px solid var(--color-border);
}

/* --------------------------------------------------------------------------
   Navigation Cards (Landing Page)
   -------------------------------------------------------------------------- */
.nav-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-xl);
}

.nav-card {
  display: block;
  text-decoration: none;
  color: inherit;
}

.nav-card__icon {
  font-size: var(--font-size-4xl);
  margin-bottom: var(--spacing-md);
}

.nav-card__title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-sm);
}

.nav-card__description {
  color: var(--color-text-light);
  font-size: var(--font-size-sm);
}

.nav-card--coming-soon {
  opacity: 0.6;
}

.nav-card--coming-soon .nav-card__title::after {
  content: ' (Coming Soon)';
  font-size: var(--font-size-sm);
  font-weight: 400;
  color: var(--color-text-muted);
}

/* --------------------------------------------------------------------------
   Value Propositions
   -------------------------------------------------------------------------- */
.value-props {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-lg);
  margin-top: var(--spacing-2xl);
}

.value-prop {
  text-align: center;
  padding: var(--spacing-lg);
}

.value-prop__icon {
  font-size: var(--font-size-3xl);
  margin-bottom: var(--spacing-sm);
}

.value-prop__title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.value-prop__description {
  color: var(--color-text-light);
  font-size: var(--font-size-sm);
}

/* --------------------------------------------------------------------------
   Use Cases Section
   -------------------------------------------------------------------------- */
.section-title {
  text-align: center;
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-xl);
  color: var(--color-text);
}

.use-cases {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
}

.use-cases-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-lg);
}

.use-case {
  background-color: var(--color-surface);
  border-radius: var(--radius-md);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-sm);
}

.use-case h3 {
  font-size: var(--font-size-lg);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
}

.use-case p {
  color: var(--color-text-light);
  font-size: var(--font-size-sm);
  margin: 0;
}

/* --------------------------------------------------------------------------
   Buttons
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-lg);
  font-family: inherit;
  font-size: var(--font-size-base);
  font-weight: 500;
  line-height: 1.5;
  text-decoration: none;
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  min-height: 44px; /* Touch target size */
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn--primary {
  background-color: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}

.btn--primary:hover:not(:disabled) {
  background-color: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
}

.btn--secondary {
  background-color: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.btn--secondary:hover:not(:disabled) {
  background-color: var(--color-primary);
  color: white;
}

.btn--large {
  padding: var(--spacing-md) var(--spacing-xl);
  font-size: var(--font-size-lg);
}

.btn--small {
  padding: var(--spacing-xs) var(--spacing-md);
  font-size: var(--font-size-sm);
  min-height: 36px;
}

/* --------------------------------------------------------------------------
   Form Controls
   -------------------------------------------------------------------------- */
.form-group {
  margin-bottom: var(--spacing-md);
}

.form-label {
  display: block;
  font-weight: 500;
  margin-bottom: var(--spacing-xs);
  font-size: var(--font-size-sm);
}

.form-select,
.form-input {
  width: 100%;
  padding: var(--spacing-sm) var(--spacing-md);
  font-family: inherit;
  font-size: var(--font-size-base);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-surface);
  color: var(--color-text);
  min-height: 44px;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-select:focus,
.form-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(107, 70, 193, 0.2);
}

.form-checkbox-group {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

.form-checkbox {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
}

.form-checkbox input[type="checkbox"] {
  width: 18px;
  height: 18px;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   Puzzle Generator Controls
   -------------------------------------------------------------------------- */
.controls {
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.controls__row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-md);
}

.controls__row:last-child {
  margin-bottom: 0;
}

.controls__field {
  flex: 1;
  min-width: 150px;
}

.controls__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-md);
}

/* --------------------------------------------------------------------------
   Advanced Options (Collapsible)
   -------------------------------------------------------------------------- */
.advanced-toggle {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  background: none;
  border: none;
  font-family: inherit;
  font-size: var(--font-size-base);
  color: var(--color-primary);
  cursor: pointer;
  padding: var(--spacing-sm) 0;
  margin-top: var(--spacing-md);
}

.advanced-toggle:hover {
  color: var(--color-primary-dark);
}

.advanced-toggle__icon {
  transition: transform var(--transition-base);
}

.advanced-toggle[aria-expanded="true"] .advanced-toggle__icon {
  transform: rotate(180deg);
}

.advanced-section {
  margin-top: var(--spacing-xl);
}

.advanced-options {
  display: none;
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-md);
}

.advanced-options.is-visible {
  display: block;
}

.advanced-options__section {
  margin-bottom: var(--spacing-lg);
}

.advanced-options__section:last-child {
  margin-bottom: 0;
}

.advanced-options__title {
  font-size: var(--font-size-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-light);
  margin-bottom: var(--spacing-md);
}

/* --------------------------------------------------------------------------
   Affiliate Banner
   -------------------------------------------------------------------------- */
.affiliate-banner {
  background-color: #fef5e7;
  border: 1px solid #f6e05e;
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.affiliate-banner__title {
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
}

.affiliate-banner__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm) var(--spacing-md);
  margin-bottom: var(--spacing-sm);
}

.affiliate-banner__link {
  display: inline-block;
  color: var(--color-primary);
  font-weight: 500;
  text-decoration: none;
}

.affiliate-banner__link:hover {
  text-decoration: underline;
}

.affiliate-banner__disclosure {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  margin: 0;
}

/* --------------------------------------------------------------------------
   Puzzle Grid (Sudoku)
   -------------------------------------------------------------------------- */
.puzzle-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 70vh;
  padding: var(--spacing-lg);
}

/* 1 puzzle: large and centered vertically */
.puzzle-container--one {
  justify-content: center;
}

/* 2 puzzles: stacked column */
.puzzle-container--two {
  gap: var(--spacing-xl);
}

.puzzle-container--two .puzzle-item {
  width: auto;
}

/* 4 puzzles: 2x2 grid */
.puzzle-container--four {
  flex-direction: row;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--spacing-xl);
}

.puzzle-container--four .puzzle-item {
  width: calc(50% - var(--spacing-xl));
  max-width: 450px;
  min-width: 280px;
}

.puzzle-item {
  text-align: center;
}

.solution-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 70vh;
  padding: var(--spacing-lg);
}

/* 1 solution: large and centered vertically */
.solution-section--one {
  justify-content: center;
}

/* 2 solutions: stacked column */
.solution-section--two {
  gap: var(--spacing-xl);
}

.solution-section--two .puzzle-item {
  width: auto;
}

/* 4 solutions: 2x2 grid */
.solution-section--four {
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--spacing-xl);
}

.solution-section--four .puzzle-item {
  width: calc(50% - var(--spacing-xl));
  max-width: 450px;
  min-width: 280px;
}

.puzzle-item .puzzle-title,
.puzzle-item .solution-title {
  margin-bottom: var(--spacing-sm);
}

.puzzle-title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-md);
  color: var(--color-text);
}

.sudoku-grid {
  border-collapse: collapse;
  background-color: var(--color-surface);
  margin: 0 auto;
  border: 3px solid var(--color-text);
}

.sudoku-grid td {
  width: 44px;
  height: 44px;
  text-align: center;
  vertical-align: middle;
  font-size: var(--font-size-xl);
  font-weight: 400;
  border: 1px solid var(--color-border-dark);
}

/* Given numbers (pre-filled by puzzle generator) */
.sudoku-grid td.given {
  font-weight: 700;
  background-color: var(--color-bg);
  color: var(--color-text);
}

/* User-entered numbers (editable cells) */
.sudoku-grid td.editable {
  color: var(--color-primary);
}

/* Box borders for different grid sizes */
/* 4x4 grid (2x2 boxes) */
.sudoku-grid--4x4 td:nth-child(2n) {
  border-right-width: 3px;
}
.sudoku-grid--4x4 tr:nth-child(2n) td {
  border-bottom-width: 3px;
}
.sudoku-grid--4x4 td:first-child {
  border-left-width: 3px;
}
.sudoku-grid--4x4 tr:first-child td {
  border-top-width: 3px;
}
.sudoku-grid--4x4 td:last-child {
  border-right-width: 3px;
}
.sudoku-grid--4x4 tr:last-child td {
  border-bottom-width: 3px;
}

/* 6x6 grid (2x3 boxes) */
.sudoku-grid--6x6 td:nth-child(3n) {
  border-right-width: 3px;
}
.sudoku-grid--6x6 tr:nth-child(2n) td {
  border-bottom-width: 3px;
}
.sudoku-grid--6x6 td:first-child {
  border-left-width: 3px;
}
.sudoku-grid--6x6 tr:first-child td {
  border-top-width: 3px;
}
.sudoku-grid--6x6 td:last-child {
  border-right-width: 3px;
}
.sudoku-grid--6x6 tr:last-child td {
  border-bottom-width: 3px;
}

/* 9x9 grid (3x3 boxes) */
.sudoku-grid--9x9 td:nth-child(3n) {
  border-right-width: 3px;
}
.sudoku-grid--9x9 tr:nth-child(3n) td {
  border-bottom-width: 3px;
}
.sudoku-grid--9x9 td:first-child {
  border-left-width: 3px;
}
.sudoku-grid--9x9 tr:first-child td {
  border-top-width: 3px;
}
.sudoku-grid--9x9 td:last-child {
  border-right-width: 3px;
}
.sudoku-grid--9x9 tr:last-child td {
  border-bottom-width: 3px;
}



/* --------------------------------------------------------------------------
   Responsive Adjustments
   -------------------------------------------------------------------------- */
@media (max-width: 768px) {
  .header__logo {
    font-size: var(--font-size-2xl);
  }
  
  .header__tagline {
    font-size: var(--font-size-base);
  }
  
  .nav-cards {
    grid-template-columns: 1fr;
  }
  
  .controls__row {
    flex-direction: column;
  }
  
  .controls__field {
    width: 100%;
    min-width: auto;
  }
}

@media (max-width: 480px) {
  .sudoku-grid td {
    width: 36px;
    height: 36px;
    font-size: var(--font-size-lg);
  }
  
  .btn--large {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
  }
}

/* --------------------------------------------------------------------------
   Print Styles
   -------------------------------------------------------------------------- */
@media print {
  /* Page setup - no headers/footers from browser */
  @page {
    margin: 15mm;
    size: auto;
  }
  
  /* Hide all UI chrome */
  .page-title,
  .header,
  .footer,
  .controls,
  .affiliate-banner,
  .advanced-options,
  .advanced-toggle,
  .btn {
    display: none !important;
  }
  
  /* Print-only page header - shown via JavaScript */
  .print-header {
    display: flex !important;
    flex-direction: column;
    align-items: center;
    padding: 10px 0 20px 0;
    margin-bottom: 10px;
  }
  
  .print-header__logo {
    height: 40px;
    width: auto;
    margin-bottom: 5px;
  }
  
  .print-header__text {
    text-align: center;
  }
  
  .print-header__title {
    font-size: 14pt;
    font-weight: bold;
    margin: 0;
  }
  
  .print-header__url {
    font-size: 10pt;
    margin: 3px 0 0 0;
    color: #666;
  }
  
  /* Reset body for print */
  body {
    background: white;
    margin: 0;
    padding: 0;
  }
  
  .puzzle-container {
    padding: 0 !important;
  }
  
  .puzzle-container::before,
  .puzzle-container::after,
  .solution-section::before,
  .solution-section::after {
    display: none !important;
  }
  
  /* Show only puzzle container */
  .main-content {
    padding: 0;
  }
  
  /* Puzzle titles - just number for each puzzle */
  .puzzle-title {
    font-size: 12pt;
    font-weight: bold;
    margin-bottom: 5px;
    margin-top: 10px;
  }
  
  .puzzle-item:first-child .puzzle-title {
    margin-top: 0;
  }
  
  /* Solution titles - just number for each solution */
  .solution-title {
    font-size: 12pt;
    font-weight: bold;
    margin-top: 10px;
    margin-bottom: 5px;
  }
  
  /* Puzzle grid print optimization */
  .sudoku-grid {
    width: auto;
    margin: 0 auto;
    page-break-inside: avoid;
  }
  
  .sudoku-grid td {
    width: 40px;
    height: 40px;
    font-size: 18pt;
  }
  
  /* Solution page */
  .solution-section {
    page-break-before: always;
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  
  .solution-section .print-header {
    display: block !important;
    padding: 10px 0 20px 0;
    margin-bottom: 10px;
  }
  
  .solution-title {
    font-size: 12pt;
    font-weight: bold;
    margin-top: 10px;
    margin-bottom: 5px;
  }
  
  /* 1 puzzle: centered and larger */
  .puzzle-container--one,
  .solution-section--one {
    min-height: auto;
    justify-content: center;
    padding: 40px 20px;
  }
  
  .puzzle-container--one .sudoku-grid td,
  .solution-section--one .sudoku-grid td {
    width: 48px;
    height: 48px;
    font-size: 20pt;
  }
  
  /* 2 puzzles: stack vertically, fit on one page */
  .puzzle-container--two,
  .solution-section--two {
    gap: 15px;
  }
  
  .puzzle-container--two .puzzle-item,
  .solution-section--two .puzzle-item {
    page-break-inside: avoid;
  }
  
  /* 4 puzzles: 2x2 grid */
  .puzzle-container--four,
  .solution-section--four {
    display: flex !important;
    flex-direction: row !important;
    flex-wrap: wrap !important;
    justify-content: center;
    gap: 10px;
  }
  
  .puzzle-container--four .puzzle-item,
  .solution-section--four .puzzle-item {
    width: 45%;
    max-width: 320px;
    page-break-inside: avoid;
    margin: 0;
  }
  
  /* Smaller grid cells for multi-puzzle print */
  .puzzle-container--two .sudoku-grid td,
  .solution-section--two .sudoku-grid td,
  .puzzle-container--four .sudoku-grid td,
  .solution-section--four .sudoku-grid td {
    width: 28px;
    height: 28px;
    font-size: 12pt;
  }
}

/* --------------------------------------------------------------------------
   Shared Puzzle Components
   -------------------------------------------------------------------------- */

/* Progress bar for bulk generation */
.progress-container {
  margin-top: var(--spacing-md);
}

.progress-bar {
  width: 100%;
  height: 8px;
  background-color: var(--color-border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.progress-bar__fill {
  height: 100%;
  background-color: var(--color-primary);
  transition: width var(--transition-base);
}

.progress-text {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  margin-top: var(--spacing-xs);
}

/* License notice for KDP */
.license-notice {
  background-color: #c6f6d5;
  border: 1px solid var(--color-success);
  border-radius: var(--radius-md);
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--font-size-sm);
  color: #22543d;
  margin-top: var(--spacing-md);
}

/* --------------------------------------------------------------------------
   Utility Classes
   -------------------------------------------------------------------------- */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

.hidden { display: none; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;

/* --------------------------------------------------------------------------
   Ad Slot Placeholders (AdSense Ready)
   -------------------------------------------------------------------------- */

/* Vertical sidebar ads - left and right margins */
.ad-slot {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 160px;
  min-height: 300px;
  background-color: var(--color-bg);
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-md);
  text-align: center;
  padding: var(--spacing-md);
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

/* Show ads when AdSense is active */
.ads-active .ad-slot {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  border: none;
  background: transparent;
}

/* Left sidebar ad */
.ad-slot--sidebar-left {
  position: fixed;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 100;
  background-color: var(--color-bg);
  border: 2px dashed var(--color-border);
}

/* Right sidebar ad */
.ad-slot--sidebar-right {
  position: fixed;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 100;
  background-color: var(--color-bg);
  border: 2px dashed var(--color-border);
}

/* Hide ads on mobile (too narrow) */
@media (max-width: 768px) {
  .ad-slot--sidebar-left,
  .ad-slot--sidebar-right {
    display: none !important;
  }
}

/* In-content ad (for between sections) */
.ad-slot--inline {
  width: 100%;
  max-width: 728px;
  min-height: 90px;
  margin: var(--spacing-xl) auto;
}

.ads-active .ad-slot--inline {
  display: block;
}

/* Mobile ad slot */
.ad-slot--mobile {
  display: none;
  width: 100%;
  min-height: 50px;
  margin: var(--spacing-md) 0;
}

@media (max-width: 768px) {
  .ads-active .ad-slot--mobile {
    display: block;
  }
}

/* Screen reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}