/* Trí Tuệ Nhỏ - Educational Game Styles */
/* Modern CSS with custom properties and animations */

:root {
    /* Color Palette */
    --primary-color: #667eea;
    --primary-dark: #5a6fd8;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --success-color: #4CAF50;
    --warning-color: #FF9800;
    --error-color: #F44336;
    --info-color: #2196F3;
    
    /* Background Colors */
    --bg-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --bg-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --bg-success: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --bg-card: rgba(255, 255, 255, 0.95);
    --bg-overlay: rgba(0, 0, 0, 0.3);
    
    /* Text Colors */
    --text-primary: #2c3e50;
    --text-secondary: #7f8c8d;
    --text-white: #ffffff;
    --text-light: #ecf0f1;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-full: 50%;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.2);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Font Sizes */
    --font-xs: 0.75rem;
    --font-sm: 0.875rem;
    --font-base: 1rem;
    --font-lg: 1.125rem;
    --font-xl: 1.25rem;
    --font-2xl: 1.5rem;
    --font-3xl: 1.875rem;
    --font-4xl: 2.25rem;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Nunito', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
    position: relative;
}

/* Loading Screen */
.loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    transition: opacity var(--transition-slow);
}

.loading-content {
    text-align: center;
    color: var(--text-white);
}

.logo-animation {
    margin-bottom: var(--spacing-xl);
}

.brain-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
    animation: pulse 2s ease-in-out infinite;
}

.loading-content h2 {
    font-size: var(--font-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-top: 4px solid var(--text-white);
    border-radius: var(--radius-full);
    animation: spin 1s linear infinite;
    margin: var(--spacing-xl) auto var(--spacing-lg);
}

.loading-text {
    font-size: var(--font-lg);
    margin-bottom: var(--spacing-lg);
    opacity: 0.8;
}

.loading-progress {
    width: 200px;
    height: 4px;
    background: rgba(255, 255, 255, 0.3);
    border-radius: var(--radius-sm);
    overflow: hidden;
    margin: 0 auto;
}

.loading-progress-bar {
    height: 100%;
    background: var(--text-white);
    transition: width var(--transition-normal);
    border-radius: var(--radius-sm);
}

/* Background Effects */
.background-effects {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

.floating-shapes {
    position: absolute;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

.floating-shapes::before,
.floating-shapes::after {
    content: '';
    position: absolute;
    width: 300px;
    height: 300px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-full);
    animation: float 20s ease-in-out infinite;
}

.floating-shapes::before {
    top: -150px;
    left: -150px;
    animation-delay: 0s;
}

.floating-shapes::after {
    bottom: -150px;
    right: -150px;
    animation-delay: 10s;
}

.particles {
    position: absolute;
    width: 100%;
    height: 100%;
}

.particle {
    position: absolute;
    font-size: var(--font-lg);
    opacity: 0.6;
    color: rgba(255, 255, 255, 0.8);
    animation: particleFloat 15s linear infinite;
}

/* Sound Toggle */
.sound-toggle {
    position: fixed;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: var(--radius-full);
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    z-index: 1000;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.sound-toggle:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-xl);
}

.sound-icon {
    font-size: var(--font-xl);
}

.sound-waves {
    display: flex;
    gap: 2px;
}

.wave {
    width: 3px;
    height: 15px;
    background: var(--primary-color);
    border-radius: var(--radius-sm);
    animation: wave 1.5s ease-in-out infinite;
}

.wave:nth-child(2) {
    animation-delay: 0.1s;
}

.wave:nth-child(3) {
    animation-delay: 0.2s;
}

/* Main Container */
.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
    z-index: 1;
}

/* Screen Management */
.screen {
    flex: 1;
    padding: var(--spacing-xl);
    animation: fadeIn var(--transition-slow);
}

/* Main Menu */
.menu-header {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.logo {
    background: var(--bg-card);
    padding: var(--spacing-xxl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    display: inline-block;
    animation: slideInDown var(--transition-slow);
}

.logo-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
}

.logo h1 {
    font-size: var(--font-4xl);
    font-weight: 800;
    background: var(--bg-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-sm);
}

.logo p {
    color: var(--text-secondary);
    font-size: var(--font-lg);
    font-weight: 500;
}

.menu-content {
    max-width: 1200px;
    margin: 0 auto;
}

/* Game Modes Grid */
.game-modes {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xxl);
}

.mode-card {
    background: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 3px solid transparent;
    animation: slideInUp var(--transition-slow);
}

.mode-card:nth-child(1) { animation-delay: 0.1s; }
.mode-card:nth-child(2) { animation-delay: 0.2s; }
.mode-card:nth-child(3) { animation-delay: 0.3s; }
.mode-card:nth-child(4) { animation-delay: 0.4s; }

.mode-card:hover {
    transform: translateY(-10px) scale(1.02);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.mode-card:active {
    transform: translateY(-5px) scale(0.98);
}

.mode-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-lg);
    display: block;
}

.mode-card h3 {
    font-size: var(--font-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.mode-card p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.6;
}

.mode-stats {
    background: rgba(102, 126, 234, 0.1);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-sm);
    color: var(--primary-color);
    font-weight: 600;
    font-size: var(--font-sm);
}

/* Menu Buttons */
.menu-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    max-width: 800px;
    margin: 0 auto;
}

.menu-btn {
    background: var(--bg-card);
    border: none;
    padding: var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    font-family: inherit;
    font-size: var(--font-lg);
    font-weight: 600;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.menu-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    background: var(--primary-color);
    color: var(--text-white);
}

.menu-btn:active {
    transform: translateY(0);
}

.btn-icon {
    font-size: var(--font-xl);
}

/* Screen Headers */
.screen-header {
    display: flex;
    align-items: center;
    margin-bottom: var(--spacing-xxl);
    background: var(--bg-card);
    padding: var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}

.back-btn {
    background: var(--primary-color);
    color: var(--text-white);
    border: none;
    width: 50px;
    height: 50px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    margin-right: var(--spacing-lg);
    font-size: var(--font-xl);
}

.back-btn:hover {
    background: var(--primary-dark);
    transform: scale(1.1);
}

.screen-header h2 {
    font-size: var(--font-3xl);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

/* Quiz Setup */
.setup-content {
    max-width: 800px;
    margin: 0 auto;
}

.setup-section {
    background: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-xl);
    animation: slideInLeft var(--transition-slow);
}

.setup-section h3 {
    font-size: var(--font-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

/* Subject Grid */
.subject-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-lg);
}

.subject-card {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 3px solid transparent;
}

.subject-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.subject-card.selected {
    background: var(--bg-primary);
    color: var(--text-white);
    border-color: var(--primary-dark);
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.subject-icon {
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
    display: block;
}

.subject-card span {
    font-weight: 600;
    font-size: var(--font-lg);
}

/* Level Selector */
.level-selector {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    justify-content: center;
}

.level-btn {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border: 3px solid transparent;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    font-family: inherit;
    font-size: var(--font-lg);
    font-weight: 600;
    color: var(--text-primary);
    min-width: 80px;
}

.level-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.level-btn.selected {
    background: var(--bg-primary);
    color: var(--text-white);
    border-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* Difficulty Selector */
.difficulty-selector {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.difficulty-card {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 3px solid transparent;
}

.difficulty-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.difficulty-card.selected {
    background: var(--bg-primary);
    color: var(--text-white);
    border-color: var(--primary-dark);
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.difficulty-icon {
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
    display: block;
}

.difficulty-card span {
    font-weight: 700;
    font-size: var(--font-xl);
    display: block;
    margin-bottom: var(--spacing-xs);
}

.difficulty-card small {
    opacity: 0.8;
    font-size: var(--font-sm);
}

/* Start Game Button */
.start-game-btn {
    background: var(--bg-secondary);
    color: var(--text-white);
    border: none;
    padding: var(--spacing-lg) var(--spacing-xxl);
    border-radius: var(--radius-lg);
    font-family: inherit;
    font-size: var(--font-xl);
    font-weight: 700;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin: var(--spacing-xl) auto 0;
    box-shadow: var(--shadow-lg);
    opacity: 0.5;
    transform: scale(0.95);
}

.start-game-btn:not(:disabled) {
    opacity: 1;
    transform: scale(1);
}

.start-game-btn:not(:disabled):hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-xl);
}

.start-game-btn:disabled {
    cursor: not-allowed;
}

/* Game Screen */
.game-header {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

.game-info {
    display: flex;
    gap: var(--spacing-xl);
    align-items: center;
    flex-wrap: wrap;
}

.score-display,
.progress-display,
.lives-display {
    text-align: center;
}

.score-display .label,
.progress-display .label,
.lives-display .label {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
}

.score-display .value {
    font-size: var(--font-2xl);
    font-weight: 800;
    color: var(--primary-color);
}

.progress-display {
    min-width: 200px;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: #e9ecef;
    border-radius: var(--radius-sm);
    overflow: hidden;
    margin: var(--spacing-xs) 0;
}

.progress-fill {
    height: 100%;
    background: var(--bg-success);
    transition: width var(--transition-normal);
    border-radius: var(--radius-sm);
}

.progress-text {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    font-weight: 600;
}

.hearts {
    display: flex;
    gap: var(--spacing-xs);
}

.heart {
    font-size: var(--font-xl);
    animation: heartbeat 2s ease-in-out infinite;
}

.pause-btn {
    background: var(--warning-color);
    color: var(--text-white);
    border: none;
    width: 60px;
    height: 60px;
    border-radius: var(--radius-full);
    font-size: var(--font-xl);
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-md);
}

.pause-btn:hover {
    background: #f57c00;
    transform: scale(1.1);
    box-shadow: var(--shadow-lg);
}

/* Question Container */
.question-container {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    padding: var(--spacing-xxl);
    margin-bottom: var(--spacing-xl);
    animation: slideInUp var(--transition-slow);
}

.timer-container {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.timer-circle {
    position: relative;
    width: 120px;
    height: 120px;
    margin: 0 auto;
}

.timer-svg {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.timer-background {
    fill: none;
    stroke: #e9ecef;
    stroke-width: 8;
}

.timer-progress {
    fill: none;
    stroke: var(--primary-color);
    stroke-width: 8;
    stroke-dasharray: 283;
    stroke-dashoffset: 0;
    transition: stroke-dashoffset 1s linear;
    stroke-linecap: round;
}

.timer-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: var(--font-3xl);
    font-weight: 800;
    color: var(--primary-color);
}

.question-content {
    text-align: center;
}

.question-text {
    font-size: var(--font-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-xxl);
    color: var(--text-primary);
    line-height: 1.4;
}

.answers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.answer-btn {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border: 3px solid transparent;
    padding: var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--radius-lg);
    font-family: inherit;
    font-size: var(--font-lg);
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    transition: all var(--transition-normal);
    text-align: center;
    min-height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.answer-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
}

.answer-btn.correct {
    background: var(--success-color);
    color: var(--text-white);
    border-color: #45a049;
    animation: correctAnswer 0.6s ease;
}

.answer-btn.wrong {
    background: var(--error-color);
    color: var(--text-white);
    border-color: #da190b;
    animation: wrongAnswer 0.6s ease;
}

/* Power-ups */
.power-ups {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.power-up {
    background: var(--bg-card);
    border: 3px solid var(--primary-color);
    width: 80px;
    height: 80px;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: relative;
    box-shadow: var(--shadow-md);
}

.power-up:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-lg);
    background: var(--primary-color);
    color: var(--text-white);
}

.power-up:active {
    transform: scale(0.95);
}

.power-icon {
    font-size: var(--font-xl);
    margin-bottom: var(--spacing-xs);
}

.power-count {
    position: absolute;
    top: -5px;
    right: -5px;
    background: var(--error-color);
    color: var(--text-white);
    width: 24px;
    height: 24px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-xs);
    font-weight: 700;
}

/* Results Screen */
.results-header {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.results-header h2 {
    font-size: var(--font-4xl);
    font-weight: 800;
    background: var(--bg-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.results-content {
    max-width: 600px;
    margin: 0 auto;
}

.score-summary {
    background: var(--bg-card);
    padding: var(--spacing-xxl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    text-align: center;
    margin-bottom: var(--spacing-xl);
    animation: bounceIn 1s ease;
}

.final-score {
    margin-bottom: var(--spacing-lg);
}

.score-number {
    font-size: 4rem;
    font-weight: 800;
    color: var(--primary-color);
    display: block;
}

.score-label {
    font-size: var(--font-lg);
    color: var(--text-secondary);
    font-weight: 600;
}

.rating-stars {
    margin: var(--spacing-lg) 0;
    font-size: 2rem;
}

.star {
    display: inline-block;
    margin: 0 var(--spacing-xs);
    transition: opacity var(--transition-normal);
}

.performance-text {
    font-size: var(--font-xl);
    font-weight: 700;
    color: var(--success-color);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.stat-item {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow-md);
    animation: slideInUp var(--transition-slow);
}

.stat-item:nth-child(1) { animation-delay: 0.1s; }
.stat-item:nth-child(2) { animation-delay: 0.2s; }
.stat-item:nth-child(3) { animation-delay: 0.3s; }
.stat-item:nth-child(4) { animation-delay: 0.4s; }

.stat-icon {
    font-size: var(--font-2xl);
    display: block;
    margin-bottom: var(--spacing-sm);
}

.stat-value {
    font-size: var(--font-xl);
    font-weight: 800;
    color: var(--primary-color);
    display: block;
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    font-weight: 600;
}

.achievements-section {
    background: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-xl);
    animation: slideInLeft var(--transition-slow);
}

.achievements-section h3 {
    font-size: var(--font-xl);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

.results-actions {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-lg);
}

.action-btn {
    padding: var(--spacing-lg) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-lg);
    font-family: inherit;
    font-size: var(--font-lg);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    box-shadow: var(--shadow-md);
}

.action-btn.primary {
    background: var(--bg-primary);
    color: var(--text-white);
}

.action-btn.secondary {
    background: var(--bg-card);
    color: var(--text-primary);
}

.action-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.action-btn.primary:hover {
    background: linear-gradient(135deg, #5a6fd8 0%, #6b5b95 100%);
}

.action-btn.secondary:hover {
    background: #f8f9fa;
}

/* Settings Screen */
.settings-content {
    max-width: 600px;
    margin: 0 auto;
}

.setting-group {
    background: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-xl);
    animation: slideInRight var(--transition-slow);
}

.setting-group h3 {
    font-size: var(--font-xl);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

.setting-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) 0;
    border-bottom: 1px solid #e9ecef;
}

.setting-item:last-child {
    border-bottom: none;
}

.setting-item label {
    font-weight: 600;
    color: var(--text-primary);
}

.toggle-switch {
    position: relative;
    width: 60px;
    height: 30px;
}

.toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.toggle-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: var(--transition-normal);
    border-radius: 30px;
}

.toggle-slider:before {
    position: absolute;
    content: "";
    height: 22px;
    width: 22px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: var(--transition-normal);
    border-radius: 50%;
}

input:checked + .toggle-slider {
    background-color: var(--primary-color);
}

input:checked + .toggle-slider:before {
    transform: translateX(30px);
}

.volume-slider {
    width: 150px;
    height: 6px;
    border-radius: 3px;
    background: #e9ecef;
    outline: none;
    -webkit-appearance: none;
    appearance: none;
}

.volume-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
}

.volume-slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    border: none;
}

.volume-value {
    margin-left: var(--spacing-md);
    font-weight: 600;
    color: var(--primary-color);
    min-width: 40px;
}

.danger-btn {
    background: var(--error-color);
    color: var(--text-white);
    border: none;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    font-family: inherit;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    box-shadow: var(--shadow-md);
}

.danger-btn:hover {
    background: #da190b;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.secondary-btn {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 2px solid var(--primary-color);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    font-family: inherit;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    box-shadow: var(--shadow-md);
    margin-top: var(--spacing-md);
}

.secondary-btn:hover {
    background: var(--primary-color);
    color: var(--text-white);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Notification System */
.notification-container {
    position: fixed;
    top: var(--spacing-lg);
    left: 50%;
    transform: translateX(-50%);
    z-index: 9998;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.notification {
    background: var(--bg-card);
    padding: var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    font-weight: 600;
    animation: slideInDown var(--transition-normal);
    max-width: 400px;
    text-align: center;
}

.notification.success {
    background: var(--success-color);
    color: var(--text-white);
}

.notification.warning {
    background: var(--warning-color);
    color: var(--text-white);
}

.notification.error {
    background: var(--error-color);
    color: var(--text-white);
}

.notification.info {
    background: var(--info-color);
    color: var(--text-white);
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes bounceIn {
    0% {
        opacity: 0;
        transform: scale(0.3);
    }
    50% {
        opacity: 1;
        transform: scale(1.05);
    }
    70% {
        transform: scale(0.9);
    }
    100% {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes float {
    0%, 100% {
        transform: translate(0, 0) rotate(0deg);
    }
    33% {
        transform: translate(30px, -30px) rotate(120deg);
    }
    66% {
        transform: translate(-20px, 20px) rotate(240deg);
    }
}

@keyframes particleFloat {
    0% {
        transform: translateY(100vh) rotate(0deg);
        opacity: 0;
    }
    10% {
        opacity: 1;
    }
    90% {
        opacity: 1;
    }
    100% {
        transform: translateY(-100px) rotate(360deg);
        opacity: 0;
    }
}

@keyframes wave {
    0%, 100% {
        transform: scaleY(1);
    }
    50% {
        transform: scaleY(1.5);
    }
}

@keyframes heartbeat {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
}

@keyframes correctAnswer {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
    100% {
        transform: scale(1);
    }
}

@keyframes wrongAnswer {
    0%, 100% {
        transform: translateX(0);
    }
    25% {
        transform: translateX(-5px);
    }
    75% {
        transform: translateX(5px);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    :root {
        --spacing-xl: 1.5rem;
        --spacing-xxl: 2rem;
        --font-3xl: 1.5rem;
        --font-4xl: 2rem;
    }

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

    .game-modes {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }

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

    .menu-buttons {
        grid-template-columns: 1fr;
    }

    .game-header {
        flex-direction: column;
        text-align: center;
    }

    .game-info {
        justify-content: center;
        gap: var(--spacing-lg);
    }

    .answers-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }

    .power-ups {
        gap: var(--spacing-md);
    }

    .power-up {
        width: 60px;
        height: 60px;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .results-actions {
        grid-template-columns: 1fr;
    }

    .notification-container {
        left: var(--spacing-lg);
        right: var(--spacing-lg);
        transform: none;
    }

    .notification {
        max-width: none;
    }
}

@media (max-width: 480px) {
    .subject-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .difficulty-selector {
        grid-template-columns: 1fr;
    }

    .level-selector {
        justify-content: space-between;
    }

    .level-btn {
        flex: 1;
        min-width: auto;
    }

    .timer-circle {
        width: 100px;
        height: 100px;
    }

    .timer-text {
        font-size: var(--font-2xl);
    }

    .question-text {
        font-size: var(--font-xl);
    }

    .answer-btn {
        padding: var(--spacing-md);
        font-size: var(--font-base);
        min-height: 60px;
    }
}

/* Print Styles */
@media print {
    .sound-toggle,
    .notification-container,
    .power-ups,
    .pause-btn {
        display: none !important;
    }

    body {
        background: white !important;
        color: black !important;
    }

    .screen {
        box-shadow: none !important;
        background: white !important;
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --bg-primary: #000000;
        --bg-card: #ffffff;
        --text-primary: #000000;
        --text-white: #ffffff;
        --primary-color: #0066cc;
    }

    .mode-card:hover,
    .answer-btn:hover {
        border-width: 4px;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    .loading-spinner {
        animation: none;
    }

    .floating-shapes::before,
    .floating-shapes::after {
        animation: none;
    }
}

/* =============================================
   MEMORY GAME STYLES
   ============================================= */

.theme-selector,
.memory-difficulty-selector {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.theme-card,
.memory-difficulty-card {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 2px solid transparent;
    box-shadow: var(--shadow-sm);
}

.theme-card:hover,
.memory-difficulty-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.theme-card.selected,
.memory-difficulty-card.selected {
    background: var(--primary-color);
    color: var(--text-white);
    border-color: var(--primary-dark);
}

.theme-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.memory-board {
    display: grid;
    gap: var(--spacing-sm);
    padding: var(--spacing-xl);
    max-width: 600px;
    margin: 0 auto;
    perspective: 1000px;
}

.memory-board.easy {
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(3, 1fr);
}

.memory-board.medium {
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(4, 1fr);
}

.memory-board.hard {
    grid-template-columns: repeat(6, 1fr);
    grid-template-rows: repeat(4, 1fr);
}

.memory-card {
    aspect-ratio: 1;
    background: var(--bg-card);
    border-radius: var(--radius-md);
    cursor: pointer;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    box-shadow: var(--shadow-md);
}

.memory-card.flipped {
    transform: rotateY(180deg);
}

.memory-card.matched {
    opacity: 0.7;
    cursor: not-allowed;
}

.memory-card .card-face {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: bold;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

.memory-card .card-back {
    background: var(--bg-secondary);
    color: var(--text-white);
}

.memory-card .card-front {
    background: var(--bg-card);
    color: var(--text-primary);
    transform: rotateY(180deg);
}

.moves-display,
.pairs-display {
    text-align: center;
}

.moves-display .label,
.pairs-display .label {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
}

.moves-display .value,
.pairs-display .value {
    font-size: var(--font-xl);
    font-weight: 800;
    color: var(--primary-color);
}

/* =============================================
   PUZZLE GAME STYLES
   ============================================= */

.puzzle-image-selector,
.puzzle-pieces-selector {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.puzzle-image-card,
.pieces-option {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 2px solid transparent;
    box-shadow: var(--shadow-sm);
}

.puzzle-image-card:hover,
.pieces-option:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.puzzle-image-card.selected,
.pieces-option.selected {
    background: var(--primary-color);
    color: var(--text-white);
    border-color: var(--primary-dark);
}

.image-preview {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.pieces-number {
    font-size: var(--font-2xl);
    font-weight: 700;
    display: block;
    margin-bottom: var(--spacing-sm);
}

.puzzle-container {
    display: flex;
    gap: var(--spacing-xl);
    padding: var(--spacing-xl);
    align-items: flex-start;
}

.puzzle-board {
    display: grid;
    gap: 2px;
    background: var(--text-secondary);
    padding: 2px;
    border-radius: var(--radius-md);
    flex: 1;
    max-width: 500px;
}

.puzzle-board.size-3 {
    grid-template-columns: repeat(3, 1fr);
}

.puzzle-board.size-4 {
    grid-template-columns: repeat(4, 1fr);
}

.puzzle-board.size-5 {
    grid-template-columns: repeat(5, 1fr);
}

.puzzle-piece {
    aspect-ratio: 1;
    background: var(--bg-card);
    border: 1px solid var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    position: relative;
    overflow: hidden;
}

.puzzle-piece .piece-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    position: relative;
}

.puzzle-piece .piece-emoji {
    font-size: 1.5em;
    opacity: 0.6;
    margin-bottom: 2px;
}

.puzzle-piece .piece-number {
    position: absolute;
    bottom: 2px;
    right: 4px;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    font-size: 0.7em;
    padding: 1px 4px;
    border-radius: 3px;
    font-weight: bold;
    z-index: 10;
}

.puzzle-piece:hover {
    background: var(--primary-color);
    color: var(--text-white);
}

.puzzle-piece.empty {
    background: var(--bg-overlay);
    cursor: default;
}

.puzzle-piece.correct {
    background: var(--success-color);
    color: var(--text-white);
}

.puzzle-preview {
    width: 200px;
    flex-shrink: 0;
}

.puzzle-preview h4 {
    text-align: center;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.preview-image {
    width: 100%;
    aspect-ratio: 1;
    background: var(--bg-card);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    box-shadow: var(--shadow-md);
}

/* =============================================
   TYPING GAME STYLES
   ============================================= */

.text-type-selector,
.typing-difficulty-selector {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.text-type-card,
.typing-difficulty-card {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 2px solid transparent;
    box-shadow: var(--shadow-sm);
}

.text-type-card:hover,
.typing-difficulty-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.text-type-card.selected,
.typing-difficulty-card.selected {
    background: var(--primary-color);
    color: var(--text-white);
    border-color: var(--primary-dark);
}

.type-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.typing-container {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-xl);
}

.text-to-type {
    background: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    font-size: var(--font-lg);
    line-height: 1.8;
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
    position: relative;
    font-family: 'Courier New', monospace;
}

.text-to-type .char {
    position: relative;
}

.text-to-type .char.correct {
    background: var(--success-color);
    color: white;
}

.text-to-type .char.incorrect {
    background: var(--error-color);
    color: white;
}

.text-to-type .char.current {
    background: var(--primary-color);
    color: white;
    animation: blink 1s infinite;
}

@keyframes blink {
    50% { opacity: 0.5; }
}

.typing-input-container {
    margin-bottom: var(--spacing-xl);
}

#typingInput {
    width: 100%;
    min-height: 120px;
    padding: var(--spacing-lg);
    border: 2px solid var(--text-secondary);
    border-radius: var(--radius-lg);
    font-size: var(--font-lg);
    font-family: 'Courier New', monospace;
    line-height: 1.8;
    resize: vertical;
    transition: border-color var(--transition-normal);
}

#typingInput:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.typing-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.stat-item {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    text-align: center;
    box-shadow: var(--shadow-sm);
}

.stat-label {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
}

.stat-value {
    font-size: var(--font-xl);
    font-weight: 800;
    color: var(--primary-color);
}

.accuracy-display {
    text-align: center;
}

.accuracy-display .label {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
}

.accuracy-display .value {
    font-size: var(--font-xl);
    font-weight: 800;
    color: var(--success-color);
}

.timer-display {
    text-align: center;
}

.timer-display .label {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
}

.timer-display .value {
    font-size: var(--font-2xl);
    font-weight: 800;
    color: var(--primary-color);
}

/* =============================================
   RESPONSIVE DESIGN FOR NEW GAMES
   ============================================= */

@media (max-width: 768px) {    .puzzle-container {
        flex-direction: column;
        align-items: center;
    }
    
    .puzzle-preview {
        width: 150px;
        margin-bottom: var(--spacing-lg);
    }
    
    .memory-board {
        padding: var(--spacing-lg);
        max-width: 100%;
    }
    
    .typing-container {
        padding: var(--spacing-lg);
    }
    
    .text-to-type {
        font-size: var(--font-md);
        padding: var(--spacing-lg);
    }
    
    #typingInput {
        font-size: var(--font-md);
        min-height: 100px;
    }
}