:root {
    --primary: #667eea;
    --primary-dark: #5568d3;
    --secondary: #764ba2;
    --success: #2ecc71;
    --error: #e74c3c;
    --warning: #f39c12;
    --dark: #2c3e50;
    --light: #ecf0f1;
    --white: #ffffff;
    --text: #2d3748;
    --text-light: #718096;
    --border: #e2e8f0;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-lg: rgba(0, 0, 0, 0.15);
    
    /* Dark mode colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;
}

[data-theme="dark"] {
    --bg-primary: #1a202c;
    --bg-secondary: #2d3748;
    --bg-tertiary: #4a5568;
    --text: #e2e8f0;
    --text-light: #a0aec0;
    --border: #4a5568;
    --shadow: rgba(0, 0, 0, 0.3);
    --shadow-lg: rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    overflow-x: hidden;
    transition: background 0.3s ease;
}

[data-theme="dark"] body {
    background: linear-gradient(135deg, #1a202c 0%, #2d3748 100%);
}

/* Particles Background */
.particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
}

.particle {
    position: absolute;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 50%;
    animation: float 15s infinite ease-in-out;
}

@keyframes float {
    0%, 100% { transform: translateY(0) translateX(0); opacity: 0; }
    10% { opacity: 1; }
    90% { opacity: 1; }
    100% { transform: translateY(-100vh) translateX(100px); opacity: 0; }
}

/* Theme Toggle - Removed */

/* Screen Containers */
.screen-container {
    width: 100%;
    max-width: 1200px;
    padding: 20px;
    position: relative;
    z-index: 1;
    animation: fadeIn 0.5s ease;
}

.hidden {
    display: none !important;
}

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

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

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

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-10px); }
    75% { transform: translateX(10px); }
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.animate-slide-up { animation: slideUp 0.6s ease; }
.animate-slide-down { animation: slideDown 0.6s ease; }
.pulse-animation { animation: pulse 2s ease-in-out infinite; }
.shake-animation { animation: shake 0.5s ease; }
.bounce-animation { animation: bounce 0.6s ease; }

/* Welcome Screen */
.welcome-card {
    background: var(--bg-primary);
    border-radius: 24px;
    padding: 50px;
    box-shadow: 0 20px 60px var(--shadow-lg);
    max-width: 800px;
    margin: 0 auto;
}

.welcome-header {
    text-align: center;
    margin-bottom: 40px;
}

.welcome-title {
    font-size: 3rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 10px;
}

.welcome-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
}

/* Avatar Selection - Removed */

/* Difficulty Selection */
.difficulty-selection {
    margin-bottom: 35px;
}

.difficulty-selection h3 {
    font-size: 1.3rem;
    color: var(--text);
    margin-bottom: 20px;
    text-align: center;
}

.difficulty-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

.difficulty-btn {
    background: var(--bg-secondary);
    border: 3px solid var(--border);
    border-radius: 16px;
    padding: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.difficulty-btn:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
    box-shadow: 0 8px 20px var(--shadow-lg);
}

.difficulty-btn.active {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
}

.diff-icon {
    font-size: 2rem;
}

.diff-label {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text);
}

.diff-desc {
    font-size: 0.85rem;
    color: var(--text-light);
}

/* Mode Selection */
.mode-selection {
    margin-bottom: 35px;
}

.mode-selection h3 {
    font-size: 1.3rem;
    color: var(--text);
    margin-bottom: 20px;
    text-align: center;
}

.mode-toggle {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 15px;
}

.mode-option input[type="radio"] {
    display: none;
}

.mode-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    padding: 20px;
    background: var(--bg-secondary);
    border: 3px solid var(--border);
    border-radius: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.mode-option input[type="radio"]:checked + .mode-card {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
}

.mode-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px var(--shadow-lg);
}

.mode-icon {
    font-size: 2rem;
}

.mode-name {
    font-weight: 600;
    color: var(--text);
}

/* Start Button */
.start-btn {
    width: 100%;
    padding: 18px 40px;
    font-size: 1.3rem;
    font-weight: 700;
    color: white;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border: none;
    border-radius: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
    margin-bottom: 30px;
}

.start-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 35px rgba(102, 126, 234, 0.5);
}

.start-btn:active {
    transform: translateY(-1px);
}

/* High Scores Preview */
.high-scores-preview {
    text-align: center;
    margin-top: 30px;
}

.high-scores-preview h4 {
    font-size: 1.2rem;
    color: var(--text);
    margin-bottom: 15px;
}

.high-scores-preview ul {
    list-style: none;
    padding: 0;
}

.high-scores-preview li {
    padding: 10px;
    background: var(--bg-secondary);
    margin-bottom: 8px;
    border-radius: 10px;
    color: var(--text);
    font-weight: 500;
}

/* Quiz Container */
.quiz-container {
    background: var(--bg-primary);
    border-radius: 24px;
    padding: 40px;
    box-shadow: 0 20px 60px var(--shadow-lg);
    max-width: 900px;
    margin: 0 auto;
    position: relative;
}

/* Quiz Header */
.quiz-header {
    margin-bottom: 30px;
}

.header-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

/* Avatar Display - Removed */

#quiz-title {
    font-size: 1.8rem;
    color: var(--text);
    font-weight: 700;
}

.score-display {
    text-align: right;
}

.score-label {
    display: block;
    font-size: 0.9rem;
    color: var(--text-light);
}

#current-score {
    font-size: 2.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Progress Bar */
.progress-container {
    position: relative;
    background: var(--bg-tertiary);
    height: 12px;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 15px;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 10px;
    transition: width 0.5s ease;
    position: relative;
    overflow: hidden;
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

.progress-text {
    text-align: center;
    font-size: 0.9rem;
    color: var(--text-light);
    margin-top: 8px;
    font-weight: 600;
}

/* Streak Container */
.streak-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 12px 20px;
    background: linear-gradient(135deg, rgba(243, 156, 18, 0.1), rgba(230, 126, 34, 0.1));
    border: 2px solid var(--warning);
    border-radius: 12px;
    margin-bottom: 20px;
    animation: pulse 1.5s ease-in-out infinite;
}

.streak-icon {
    font-size: 1.5rem;
    animation: bounce 0.6s ease infinite;
}

.streak-text {
    font-weight: 700;
    color: var(--warning);
}

.streak-multiplier {
    font-size: 1.2rem;
    font-weight: 800;
    color: var(--warning);
}

/* Power-ups */
.powerups-container {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-bottom: 20px;
}

.powerup-btn {
    padding: 10px 15px;
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 12px;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 5px;
    color: var(--text);
}

.powerup-btn:hover:not(:disabled) {
    transform: translateY(-3px);
    border-color: var(--primary);
    box-shadow: 0 6px 15px var(--shadow-lg);
}

.powerup-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.powerup-count {
    background: var(--primary);
    color: white;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 700;
}

/* Timer */
.timer-container {
    position: relative;
    display: flex;
    justify-content: center;
    margin-bottom: 25px;
}

.timer-ring {
    transform: rotate(-90deg);
}

.timer-ring-progress {
    transition: stroke-dashoffset 0.5s linear;
    stroke-dasharray: 213.628;
    stroke-dashoffset: 0;
}

.timer-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text);
}

.timer-warning {
    animation: pulse 1s ease-in-out infinite;
}

/* Quiz Body */
.quiz-body {
    margin-bottom: 25px;
}

.question {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 25px;
    line-height: 1.6;
    padding: 20px;
    background: var(--bg-secondary);
    border-radius: 12px;
    border-left: 4px solid var(--primary);
    animation: slideUp 0.5s ease;
}

.question-image {
    width: 100%;
    max-width: 400px;
    border-radius: 12px;
    margin: 15px 0;
    box-shadow: 0 4px 15px var(--shadow);
}

.options {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.options label {
    display: flex;
    align-items: center;
    padding: 18px 20px;
    background: var(--bg-secondary);
    border: 3px solid var(--border);
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.1rem;
    color: var(--text);
    animation: slideUp 0.5s ease;
    animation-fill-mode: both;
}

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

.options label:hover {
    transform: translateX(10px);
    border-color: var(--primary);
    box-shadow: 0 4px 15px var(--shadow-lg);
}

.options label input[type="radio"] {
    margin-right: 15px;
    width: 22px;
    height: 22px;
    accent-color: var(--primary);
    cursor: pointer;
}

.option-text {
    flex: 1;
    color: var(--text);
}

.options label:has(input:checked) {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
    transform: translateX(10px);
}

.option-correct {
    border-color: var(--success) !important;
    background: rgba(46, 204, 113, 0.1) !important;
}

.option-wrong {
    border-color: var(--error) !important;
    background: rgba(231, 76, 60, 0.1) !important;
    animation: shake 0.5s ease !important;
}

/* Confidence Slider */
.confidence-container {
    margin: 20px 0;
    padding: 20px;
    background: var(--bg-secondary);
    border-radius: 12px;
}

.confidence-container label {
    display: block;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 15px;
}

.confidence-slider-wrapper {
    display: flex;
    align-items: center;
    gap: 15px;
}

.confidence-emoji {
    font-size: 2rem;
}

#confidence-slider {
    flex: 1;
    height: 8px;
    border-radius: 5px;
    outline: none;
    -webkit-appearance: none;
    background: var(--bg-tertiary);
}

#confidence-slider::-webkit-slider-thumb {
    appearance: none;
    -webkit-appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--primary);
    cursor: pointer;
    transition: all 0.3s ease;
}

#confidence-slider::-moz-range-thumb {
    appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--primary);
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
}

#confidence-slider::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.confidence-label {
    font-weight: 600;
    color: var(--text);
    min-width: 120px;
}

/* Feedback */
.feedback-container {
    padding: 18px 25px;
    border-radius: 12px;
    margin: 20px 0;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 12px;
    animation: slideDown 0.5s ease;
}

.feedback-container.correct {
    background: linear-gradient(135deg, rgba(46, 204, 113, 0.15), rgba(39, 174, 96, 0.15));
    border: 2px solid var(--success);
    color: #155724;
}

.feedback-container.wrong {
    background: linear-gradient(135deg, rgba(231, 76, 60, 0.15), rgba(192, 57, 43, 0.15));
    border: 2px solid var(--error);
    color: #721c24;
}

.feedback-icon {
    font-size: 1.5rem;
}

/* Explanation */
.explanation-container {
    padding: 18px 25px;
    background: var(--bg-secondary);
    border-left: 4px solid var(--primary);
    border-radius: 12px;
    margin: 15px 0;
    animation: slideUp 0.5s ease;
}

.explanation-container strong {
    color: var(--primary);
    display: block;
    margin-bottom: 8px;
}

/* Buttons */
.btn {
    padding: 14px 32px;
    font-size: 1.1rem;
    font-weight: 600;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.5);
}

.btn-success {
    background: var(--success);
    color: white;
    box-shadow: 0 6px 20px rgba(46, 204, 113, 0.4);
}

.btn-success:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(46, 204, 113, 0.5);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text);
    border: 2px solid var(--border);
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
    transform: translateY(-3px);
}

.btn-accent {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
}

.btn-accent:hover {
    transform: translateY(-3px);
}

.quiz-footer {
    display: flex;
    gap: 15px;
    justify-content: center;
}

/* Attention Warning */
.attention-warning {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--warning);
    color: white;
    padding: 20px 40px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    z-index: 1001;
    animation: shake 0.5s ease;
}

.warning-icon {
    font-size: 2rem;
    margin-right: 10px;
}

/* Result Screen */
.result-container {
    background: var(--bg-primary);
    border-radius: 24px;
    padding: 50px;
    box-shadow: 0 20px 60px var(--shadow-lg);
    max-width: 900px;
    margin: 0 auto;
}

.result-header {
    text-align: center;
    margin-bottom: 40px;
}

/* Result Avatar - Removed */

.result-title {
    font-size: 2.5rem;
    color: var(--text);
    font-weight: 800;
    margin-bottom: 30px;
}

.result-score-circle {
    position: relative;
    width: 200px;
    height: 200px;
    margin: 0 auto 30px;
}

.score-bg, .score-progress {
    transition: stroke-dashoffset 1s ease;
}

.score-progress {
    stroke-dasharray: 565.48;
    stroke-dashoffset: 565.48;
}

.score-text-center {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

.final-score {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--text);
}

.score-percentage {
    font-size: 1.2rem;
    color: var(--text-light);
    font-weight: 600;
}

.result-message {
    font-size: 1.3rem;
    color: var(--text-light);
    font-weight: 500;
}

/* Analytics Section */
.analytics-section {
    margin: 40px 0;
}

.analytics-section h3, .analytics-section h4 {
    color: var(--text);
    margin-bottom: 20px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    background: var(--bg-secondary);
    padding: 20px;
    border-radius: 16px;
    text-align: center;
    transition: all 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px var(--shadow-lg);
}

.stat-icon {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 5px;
}

.stat-value {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text);
}

/* Topic Performance */
.topic-performance {
    margin: 30px 0;
}

.topic-bar {
    margin-bottom: 15px;
}

.topic-name {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text);
}

.topic-progress {
    height: 12px;
    background: var(--bg-tertiary);
    border-radius: 10px;
    overflow: hidden;
}

.topic-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 10px;
    transition: width 1s ease;
}

/* Heatmap */
.heatmap-section {
    margin: 30px 0;
}

.heatmap-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
    gap: 10px;
}

.heatmap-cell {
    aspect-ratio: 1;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: white;
    transition: all 0.3s ease;
    cursor: pointer;
}

.heatmap-cell:hover {
    transform: scale(1.1);
}

.heatmap-easy {
    background: linear-gradient(135deg, #2ecc71, #27ae60);
}

.heatmap-medium {
    background: linear-gradient(135deg, #f39c12, #e67e22);
}

.heatmap-hard {
    background: linear-gradient(135deg, #e74c3c, #c0392b);
}

/* Answer Changes */
.answer-changes {
    margin: 30px 0;
}

.answer-changes ul {
    list-style: none;
    padding: 0;
}

.answer-changes li {
    padding: 12px 18px;
    background: var(--bg-secondary);
    margin-bottom: 10px;
    border-radius: 10px;
    border-left: 4px solid var(--warning);
    color: var(--text);
}

/* Leaderboard */
.leaderboard-section {
    margin: 40px 0;
}

.leaderboard-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.tab-btn {
    padding: 10px 20px;
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 10px;
    cursor: pointer;
    font-weight: 600;
    color: var(--text);
    transition: all 0.3s ease;
}

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

.score-list {
    list-style: none;
    padding: 0;
}

.score-list li {
    padding: 15px 20px;
    background: var(--bg-secondary);
    margin-bottom: 10px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    gap: 15px;
    color: var(--text);
    font-weight: 600;
    transition: all 0.3s ease;
}

.score-list li:hover {
    transform: translateX(10px);
}

.score-rank {
    font-size: 1.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Result Actions */
.result-actions {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-top: 30px;
    flex-wrap: wrap;
}

/* Review Screen */
.review-container {
    background: var(--bg-primary);
    border-radius: 24px;
    padding: 40px;
    box-shadow: 0 20px 60px var(--shadow-lg);
    max-width: 900px;
    margin: 0 auto;
}

.review-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

.review-header h2 {
    color: var(--text);
    font-size: 2rem;
}

.btn-close {
    background: none;
    border: none;
    font-size: 2rem;
    cursor: pointer;
    color: var(--text-light);
    transition: all 0.3s ease;
}

.btn-close:hover {
    color: var(--error);
    transform: rotate(90deg);
}

.review-content {
    margin-bottom: 30px;
}

.review-item {
    background: var(--bg-secondary);
    padding: 25px;
    border-radius: 16px;
    margin-bottom: 20px;
    animation: slideUp 0.5s ease;
}

.review-question {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 15px;
}

.review-answer {
    margin: 10px 0;
    padding: 12px;
    border-radius: 8px;
}

.review-answer.your-answer {
    background: rgba(102, 126, 234, 0.1);
    border-left: 4px solid var(--primary);
}

.review-answer.correct-answer {
    background: rgba(46, 204, 113, 0.1);
    border-left: 4px solid var(--success);
}

.review-answer.wrong-answer {
    background: rgba(231, 76, 60, 0.1);
    border-left: 4px solid var(--error);
}

/* Notification Toast */
.notification-toast {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: var(--bg-primary);
    padding: 18px 25px;
    border-radius: 12px;
    box-shadow: 0 10px 30px var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 12px;
    z-index: 1001;
    animation: slideUp 0.5s ease;
    border: 2px solid var(--border);
}

.toast-icon {
    font-size: 1.5rem;
}

.toast-message {
    color: var(--text);
    font-weight: 600;
}

/* Focus Mode - Removed */

/* Responsive Design */
@media (max-width: 768px) {
    .welcome-card, .quiz-container, .result-container, .review-container {
        padding: 25px;
        border-radius: 16px;
    }

    .welcome-title {
        font-size: 2rem;
    }

    .welcome-subtitle {
        font-size: 1rem;
    }

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

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

    .mode-toggle {
        grid-template-columns: 1fr;
    }

    .header-top {
        flex-direction: column;
        gap: 15px;
    }

    #quiz-title {
        font-size: 1.4rem;
        text-align: center;
    }

    .question {
        font-size: 1.1rem;
        padding: 15px;
    }

    .options label {
        font-size: 1rem;
        padding: 15px;
    }

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

    .result-actions {
        flex-direction: column;
    }

    .result-actions .btn {
        width: 100%;
    }

    .theme-toggle, .sound-toggle, .focus-toggle {
        width: 45px;
        height: 45px;
        top: 15px;
    }

    .theme-toggle { right: 15px; }
    .sound-toggle { right: 70px; }
    .focus-toggle { right: 125px; }

    .notification-toast {
        bottom: 20px;
        right: 20px;
        left: 20px;
    }
}

@media (max-width: 480px) {
    .avatar-option {
        font-size: 2rem;
        padding: 10px;
    }

    .powerups-container {
        flex-wrap: wrap;
    }

    .heatmap-grid {
        grid-template-columns: repeat(auto-fill, minmax(50px, 1fr));
    }
}

/* Print Styles */
@media print {
    .theme-toggle, .sound-toggle, .focus-toggle,
    .particles, .result-actions {
        display: none;
    }

    body {
        background: white;
    }

    .result-container {
        box-shadow: none;
    }
}

.hidden { display: none; }