/* Step-by-Step Solutions Styles */
/* ═══════════════════════════════════════════════════════════════════════════════
   🎨 TopPuzzles Brand Identity Colors
   Primary: #2563EB (Blue) | Secondary: #F59E08 (Orange/Gold)
   ═══════════════════════════════════════════════════════════════════════════════ */

:root {
    /* Brand Identity */
    --brand-primary: #2563EB;
    --brand-primary-light: #3B82F6;
    --brand-primary-dark: #1D4ED8;
    --brand-secondary: #F59E08;
    --brand-secondary-light: #FBBF24;
    --brand-secondary-dark: #D97706;
    
    /* Level Colors (Thermal System) - Will be overridden per level */
    --level-primary: var(--brand-primary);
    --level-primary-dark: var(--brand-primary-dark);
    --level-secondary: var(--brand-primary-light);
    
    /* Legacy variable mapping */
    --primary-color: var(--brand-primary);
    --success-color: #4CAF50;
    --error-color: #F44336;
    --warning-color: #FF9800;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
}

/* ═══════════════════════════════════════════════════════════════════════════════
   Level-specific color themes (Thermal Color System)
   ═══════════════════════════════════════════════════════════════════════════════ */

/* Level 1: Beginner - Green (Cool, Safe, Growth) */
.level-1, [data-level="1"] {
    --level-primary: #4CAF50;
    --level-primary-dark: #388E3C;
    --level-secondary: #66BB6A;
    --primary-color: #4CAF50;
}

/* Level 2: Amateur - Lime Green (Comfortable Progress) */
.level-2, [data-level="2"] {
    --level-primary: #8BC34A;
    --level-primary-dark: #689F38;
    --level-secondary: #9CCC65;
    --primary-color: #8BC34A;
}

/* Level 3: Regular - Yellow/Gold (Attention, Challenge Begins) */
.level-3, [data-level="3"] {
    --level-primary: #FFC107;
    --level-primary-dark: #FFA000;
    --level-secondary: #FFCA28;
    --primary-color: #FFC107;
}

/* Level 4: Professional - Orange (Warning, Real Challenge) */
.level-4, [data-level="4"] {
    --level-primary: #FF9800;
    --level-primary-dark: #F57C00;
    --level-secondary: #FFB74D;
    --primary-color: #FF9800;
}

/* Level 5: Top Player - Deep Orange (Hot, Major Challenge) */
.level-5, [data-level="5"] {
    --level-primary: #FF5722;
    --level-primary-dark: #E64A19;
    --level-secondary: #FF8A65;
    --primary-color: #FF5722;
}

/* Level 6: Super Star - Red (Danger! Very Hard) */
.level-6, [data-level="6"] {
    --level-primary: #F44336;
    --level-primary-dark: #D32F2F;
    --level-secondary: #E57373;
    --primary-color: #F44336;
}

/* Level 7: Legend - Royal Purple (Legendary, Royal, Crown) */
.level-7, [data-level="7"] {
    --level-primary: #7C3AED;
    --level-primary-dark: #6D28D9;
    --level-secondary: #A78BFA;
    --primary-color: #7C3AED;
}

/* Level 8: All Levels - Blue (Neutral, Comprehensive, Trusted) */
.level-8, [data-level="8"] {
    --level-primary: #2563EB;
    --level-primary-dark: #1D4ED8;
    --level-secondary: #3B82F6;
    --primary-color: #2563EB;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    background: linear-gradient(135deg, var(--level-primary), var(--level-primary-dark));
    color: white;
    padding: 30px 20px;
    text-align: center;
    border-radius: 10px;
    margin-bottom: 20px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.header h1 {
    font-size: 1.8rem;
    margin-bottom: 10px;
}

.puzzle-meta {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
}

.meta-item {
    background: rgba(255,255,255,0.2);
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
}

/* Initial Grid */
.initial-grid {
    background: var(--card-bg);
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.initial-grid h2 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.sudoku-grid {
    max-width: 350px;
    margin: 0 auto;
}

/* Techniques Summary */
.techniques-summary {
    background: var(--card-bg);
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.techniques-summary h2 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.techniques-list {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.technique-item {
    background: var(--bg-color);
    padding: 8px 15px;
    border-radius: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.technique-count {
    background: var(--primary-color);
    color: white;
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 0.8rem;
}

/* Steps */
.steps-container {
    background: var(--card-bg);
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.steps-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
    flex-wrap: wrap;
    gap: 10px;
}

.steps-header h2 {
    color: var(--primary-color);
}

.steps-controls {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
}

.steps-controls button {
    padding: 8px 15px;
    border: 1px solid var(--border-color);
    background: white;
    border-radius: 5px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.steps-controls button:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.filter-buttons {
    display: flex;
    gap: 5px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 5px 10px;
    border: 1px solid var(--border-color);
    background: white;
    border-radius: 15px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: all 0.2s;
}

.filter-btn:hover, .filter-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* Step Item */
.step {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 10px;
    overflow: hidden;
}

.step-header {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 15px;
    background: var(--bg-color);
    cursor: pointer;
    transition: background 0.2s;
}

.step-header:hover {
    background: #e8e8e8;
}

.step-number {
    font-weight: bold;
    color: var(--primary-color);
    min-width: 40px;
}

.step-action {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 14px;
}

.step-action.place {
    background: var(--success-color);
}

.step-action.remove {
    background: var(--error-color);
}

.technique-badge {
    padding: 3px 10px;
    border-radius: 12px;
    font-size: 0.8rem;
    color: white;
}

.family-single { background: #4CAF50; }
.family-locked { background: #2196F3; }
.family-subset { background: #9C27B0; }
.family-chain { background: #FF9800; }
.family-te, .family-t-e { background: #F44336; }

.step-summary {
    flex: 1;
    font-size: 0.9rem;
    color: #666;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.step-toggle {
    color: #999;
    transition: transform 0.3s;
}

.step.open .step-toggle {
    transform: rotate(180deg);
}

.step-content {
    display: none;
    padding: 15px;
    border-top: 1px solid var(--border-color);
}

.step.open .step-content {
    display: block;
}

.step-grid {
    text-align: center;
    margin-bottom: 15px;
}

.step-grid .sudoku-grid {
    max-width: 300px;
}

.step-details p {
    margin-bottom: 5px;
}

/* Navigation */
.puzzle-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
    padding: 15px;
    background: var(--card-bg);
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.puzzle-nav a {
    color: var(--primary-color);
    text-decoration: none;
    padding: 8px 15px;
    border-radius: 5px;
    transition: background 0.2s;
}

.puzzle-nav a:hover {
    background: var(--bg-color);
}

.puzzle-nav .disabled {
    color: #ccc;
    pointer-events: none;
}

/* Index Page - Puzzles Grid */
.puzzles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 15px;
}

.puzzle-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 15px;
    text-align: center;
    text-decoration: none;
    color: var(--text-color);
    transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
}

.puzzle-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 20px rgba(0,0,0,0.15);
    border-color: var(--primary-color);
}

.puzzle-number {
    display: block;
    font-size: 1.3rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.puzzle-stats {
    font-size: 0.75rem;
    color: #666;
    line-height: 1.4;
}

/* Footer */
.footer {
    margin-top: 30px;
    padding: 20px;
    text-align: center;
    color: #666;
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 600px) {
    .container {
        padding: 10px;
    }
    
    .header h1 {
        font-size: 1.4rem;
    }
    
    .puzzle-meta {
        gap: 10px;
    }
    
    .meta-item {
        padding: 4px 10px;
        font-size: 0.8rem;
    }
    
    .step-summary {
        display: none;
    }
    
    .puzzle-nav {
        flex-direction: column;
        gap: 10px;
        text-align: center;
    }
    
    .steps-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .puzzles-grid {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
        gap: 10px;
    }
    
    .puzzle-card {
        padding: 12px;
    }
}

/* Print Styles */
@media print {
    .steps-controls,
    .filter-buttons,
    .puzzle-nav,
    .footer {
        display: none;
    }
    
    .step-content {
        display: block !important;
    }
    
    .container {
        max-width: 100%;
    }
}

/* ============================================================
   Main Index Page Styles - TopPuzzles Brand Design
   ============================================================ */

.main-header {
    background: linear-gradient(135deg, var(--brand-primary) 0%, var(--brand-primary-dark) 100%);
    color: white;
    padding: 35px 20px;
    text-align: center;
    border-radius: 12px;
    margin-bottom: 30px;
    box-shadow: 0 4px 20px rgba(37, 99, 235, 0.25);
}

.series-badge {
    display: inline-block;
    background: rgba(255, 255, 255, 0.15);
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 12px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.main-header h1 {
    font-size: 1.8rem;
    margin-bottom: 8px;
    font-weight: 600;
    letter-spacing: -0.5px;
}

.main-header .subtitle {
    font-size: 0.95rem;
    opacity: 0.85;
    font-weight: 300;
}

.total-stats {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-top: 18px;
    flex-wrap: wrap;
}

.total-stat {
    background: rgba(255,255,255,0.15);
    padding: 8px 18px;
    border-radius: 20px;
    backdrop-filter: blur(10px);
}

.total-stat .value {
    font-size: 1.4rem;
    font-weight: 700;
    display: block;
}

.total-stat .label {
    font-size: 0.75rem;
    opacity: 0.85;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.levels-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-bottom: 30px;
}

.level-card {
    background: var(--card-bg);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0,0,0,0.08);
    transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    text-decoration: none;
    color: inherit;
    border: 1px solid rgba(0,0,0,0.05);
}

.level-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.12);
    border-color: var(--primary-color);
}

.level-card-header {
    padding: 16px 12px;
    color: white;
    text-align: center;
}

.level-card-header h2 {
    font-size: 0.95rem;
    margin-bottom: 2px;
    font-weight: 600;
}

.level-card-header .difficulty {
    font-size: 0.7rem;
    opacity: 0.85;
    font-weight: 400;
}

.level-card-body {
    padding: 12px;
}

.level-card-stats {
    display: flex;
    justify-content: space-around;
    text-align: center;
}

.level-card-stat .stat-value {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--primary-color);
    display: block;
}

.level-card-stat .stat-label {
    font-size: 0.65rem;
    color: #888;
    text-transform: uppercase;
    letter-spacing: 0.3px;
}

.level-card-footer {
    padding: 10px 12px;
    background: linear-gradient(to bottom, #f8f9fa, #f0f1f2);
    text-align: center;
    border-top: 1px solid rgba(0,0,0,0.05);
}

.view-btn {
    display: inline-block;
    padding: 6px 16px;
    background: var(--primary-color);
    color: white;
    border-radius: 15px;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.75rem;
    transition: all 0.2s;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.view-btn:hover {
    background: #357abd;
    transform: scale(1.02);
}

/* Level colors - Thermal Color System (matching cover_data.py) */
.level-1 .level-card-header { background: linear-gradient(145deg, #4CAF50, #388E3C); }  /* Green - Beginner */
.level-2 .level-card-header { background: linear-gradient(145deg, #8BC34A, #689F38); }  /* Lime - Amateur */
.level-3 .level-card-header { background: linear-gradient(145deg, #FFC107, #FFA000); }  /* Yellow - Regular */
.level-4 .level-card-header { background: linear-gradient(145deg, #FF9800, #F57C00); }  /* Orange - Professional */
.level-5 .level-card-header { background: linear-gradient(145deg, #FF5722, #E64A19); }  /* Deep Orange - Top Player */
.level-6 .level-card-header { background: linear-gradient(145deg, #F44336, #D32F2F); }  /* Red - Super Star */
.level-7 .level-card-header { background: linear-gradient(145deg, #7C3AED, #6D28D9); }  /* Royal Purple - Legend */
.level-8 .level-card-header { background: linear-gradient(145deg, #2563EB, #1D4ED8); }  /* Blue - All Levels */

.footer-section {
    text-align: center;
    padding: 20px;
    color: #888;
    font-size: 0.85rem;
}

.footer-section a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.footer-section a:hover {
    text-decoration: underline;
}

/* Responsive - Main Index */
@media (max-width: 1024px) {
    .levels-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 768px) {
    .levels-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }
    
    .main-header h1 {
        font-size: 1.5rem;
    }
    
    .total-stats {
        gap: 10px;
    }
    
    .total-stat {
        padding: 6px 14px;
    }
    
    .total-stat .value {
        font-size: 1.2rem;
    }
}

@media (max-width: 480px) {
    .levels-grid {
        grid-template-columns: 1fr 1fr;
        gap: 10px;
    }
    
    .level-card-header {
        padding: 12px 10px;
    }
    
    .level-card-header h2 {
        font-size: 0.85rem;
    }
    
    .level-card-body {
        padding: 10px;
    }
    
    .level-card-stat .stat-value {
        font-size: 1rem;
    }
}

/* ============================================================
   Level Index Page Styles
   ============================================================ */

.level-header {
    background: linear-gradient(135deg, var(--level-primary), var(--level-primary-dark));
    color: white;
    padding: 40px 20px;
    text-align: center;
    border-radius: 10px;
    margin-bottom: 30px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.level-header h1 {
    font-size: 2.2rem;
    margin-bottom: 10px;
}

.level-header .subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
}

.level-stats {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-top: 20px;
    flex-wrap: wrap;
}

.stat-item {
    background: rgba(255,255,255,0.2);
    padding: 10px 25px;
    border-radius: 25px;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: bold;
    display: block;
}

.stat-label {
    font-size: 0.9rem;
    opacity: 0.9;
}

.intro-section {
    background: var(--card-bg);
    border-radius: 10px;
    padding: 25px;
    margin-bottom: 30px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.intro-section h2 {
    color: var(--primary-color);
    margin-bottom: 15px;
}

.intro-section p {
    color: #666;
    margin-bottom: 10px;
}

.puzzles-section {
    background: var(--card-bg);
    border-radius: 10px;
    padding: 25px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.puzzles-section h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
}

.back-link {
    display: inline-block;
    margin-top: 20px;
    color: var(--primary-color);
    text-decoration: none;
    padding: 10px 20px;
    border: 2px solid var(--primary-color);
    border-radius: 25px;
    transition: all 0.3s;
}

.back-link:hover {
    background: var(--primary-color);
    color: white;
}

/* Responsive for Level Index */
@media (max-width: 768px) {
    .level-header h1 {
        font-size: 1.6rem;
    }
    
    .level-stats {
        gap: 15px;
    }
    
    .stat-item {
        padding: 8px 16px;
    }
    
    .stat-value {
        font-size: 1.2rem;
    }
    
    .intro-section,
    .puzzles-section {
        padding: 18px;
    }
}