/* ===== CSS VARIABLES ===== */
:root {
    /* Light Mode Colors - Refined & Elegant */
    --bg-primary: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    --bg-secondary: #ffffff;
    --text-primary: #1a1a2e;
    --text-secondary: #6c757d;
    --accent: #4a90e2;
    --accent-hover: #357abd;
    --border: #dee2e6;
    --shadow: rgba(0, 0, 0, 0.08);
    --card-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    
    /* Transitions */
    --transition-speed: 0.3s;
}

/* ===== DARK MODE VARIABLES ===== */
body.dark-mode {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --text-primary: #e0e0e0;
    --text-secondary: #a0a0a0;
    --accent: #4a9eff;
    --accent-hover: #3a8eef;
    --border: #404040;
    --shadow: rgba(0, 0, 0, 0.3);
}

/* Easy Mode - Matrix Terminal Theme */
body.dark-mode.easy-mode {
    --bg-primary: #0d0208;
    --bg-secondary: #1a0f1a;
    --text-primary: #00ff41;
    --text-secondary: #00cc33;
    --accent: #00ff41;
    --accent-hover: #00cc33;
    --border: #00ff41;
    --matrix-green: #00ff41;
    --matrix-dark: #003b00;
    font-family: 'Courier New', 'Consolas', 'Monaco', monospace;
}

body.dark-mode.easy-mode .container {
    background: #0d0208;
    position: relative;
}

body.dark-mode.easy-mode .container::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        repeating-linear-gradient(0deg, rgba(0, 255, 65, 0.03) 0px, transparent 1px, transparent 2px, rgba(0, 255, 65, 0.03) 3px),
        repeating-linear-gradient(90deg, rgba(0, 255, 65, 0.03) 0px, transparent 1px, transparent 2px, rgba(0, 255, 65, 0.03) 3px);
    pointer-events: none;
    z-index: 1;
}

body.dark-mode.easy-mode .difficulty-card,
body.dark-mode.easy-mode .quiz-header,
body.dark-mode.easy-mode .quiz-content,
body.dark-mode.easy-mode .results-container {
    background: rgba(0, 59, 0, 0.3);
    border: 1px solid var(--matrix-green);
    box-shadow: 
        0 0 10px rgba(0, 255, 65, 0.3),
        inset 0 0 20px rgba(0, 255, 65, 0.05);
    position: relative;
}

body.dark-mode.easy-mode .difficulty-card::after,
body.dark-mode.easy-mode .quiz-header::after,
body.dark-mode.easy-mode .quiz-content::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(0, 255, 65, 0.1), transparent);
    animation: scanline 3s linear infinite;
}

@keyframes scanline {
    0% { left: -100%; }
    100% { left: 100%; }
}

body.dark-mode.easy-mode .main-title,
body.dark-mode.easy-mode .screen-title,
body.dark-mode.easy-mode .question-text {
    color: var(--matrix-green);
    text-shadow: 0 0 5px var(--matrix-green), 0 0 10px var(--matrix-green);
    font-weight: 700;
    letter-spacing: 3px;
    text-transform: uppercase;
}

body.dark-mode.easy-mode .option-btn {
    background: rgba(0, 59, 0, 0.4);
    border: 1px solid rgba(0, 255, 65, 0.5);
    color: var(--matrix-green);
    font-family: 'Courier New', monospace;
    font-weight: 600;
    position: relative;
    overflow: hidden;
}

body.dark-mode.easy-mode .option-btn::before {
    content: '> ';
    opacity: 0;
    transition: opacity 0.3s;
}

body.dark-mode.easy-mode .option-btn:hover::before {
    opacity: 1;
}

body.dark-mode.easy-mode .option-btn:hover {
    border-color: var(--matrix-green);
    background: radial-gradient(circle at center, rgba(0, 255, 65, 0.2), rgba(0, 59, 0, 0.4));
    box-shadow: 0 0 20px rgba(0, 255, 65, 0.4), inset 0 0 20px rgba(0, 255, 65, 0.2);
}

body.dark-mode.easy-mode .progress-bar {
    background: var(--matrix-green);
    box-shadow: 0 0 10px var(--matrix-green);
    animation: matrixPulse 1.5s ease-in-out infinite;
}

@keyframes matrixPulse {
    0%, 100% { box-shadow: 0 0 10px var(--matrix-green); }
    50% { box-shadow: 0 0 20px var(--matrix-green), 0 0 30px var(--matrix-green); }
}

body.dark-mode.easy-mode .select-btn,
body.dark-mode.easy-mode .nav-btn,
body.dark-mode.easy-mode .submit-btn,
body.dark-mode.easy-mode .restart-btn {
    background: rgba(0, 59, 0, 0.5);
    border: 1px solid var(--matrix-green);
    color: var(--matrix-green);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 2px;
    position: relative;
    overflow: hidden;
}

body.dark-mode.easy-mode .select-btn:hover,
body.dark-mode.easy-mode .nav-btn:hover,
body.dark-mode.easy-mode .submit-btn:hover,
body.dark-mode.easy-mode .restart-btn:hover {
    background: radial-gradient(circle at center, rgba(0, 255, 65, 0.3), rgba(0, 59, 0, 0.5));
    box-shadow: 0 0 30px rgba(0, 255, 65, 0.6), inset 0 0 30px rgba(0, 255, 65, 0.3);
    transform: translateY(-2px);
}

body.dark-mode.easy-mode .score-circle {
    background: radial-gradient(circle, #00ff41, #003b00);
    box-shadow: 0 0 50px rgba(0, 255, 65, 0.8);
    animation: scaleIn 0.6s ease-out, matrixPulse 2s ease-in-out infinite;
}

/* Medium Mode - Cyberpunk Hacker Theme */
body.dark-mode.medium-mode {
    --bg-primary: #0a0e27;
    --bg-secondary: #1a1f3a;
    --text-primary: #ff2a6d;
    --text-secondary: #05d9e8;
    --accent: #ff2a6d;
    --accent-hover: #d1f7ff;
    --border: #ff2a6d;
    --cyber-pink: #ff2a6d;
    --cyber-cyan: #05d9e8;
    --cyber-yellow: #f3ea5f;
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
}

body.dark-mode.medium-mode .container {
    background: 
        radial-gradient(ellipse at top left, rgba(255, 42, 109, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse at bottom right, rgba(5, 217, 232, 0.1) 0%, transparent 50%),
        #0a0e27;
    position: relative;
}

body.dark-mode.medium-mode .container::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        linear-gradient(rgba(255, 42, 109, 0.05) 1px, transparent 1px),
        linear-gradient(90deg, rgba(5, 217, 232, 0.05) 1px, transparent 1px);
    background-size: 50px 50px;
    pointer-events: none;
    z-index: 1;
    animation: gridMove 20s linear infinite;
}

@keyframes gridMove {
    0% { transform: translate(0, 0); }
    100% { transform: translate(50px, 50px); }
}

body.dark-mode.medium-mode .difficulty-card,
body.dark-mode.medium-mode .quiz-header,
body.dark-mode.medium-mode .quiz-content,
body.dark-mode.medium-mode .results-container {
    background: rgba(26, 31, 58, 0.8);
    border: 1px solid var(--cyber-pink);
    box-shadow: 
        0 0 20px rgba(255, 42, 109, 0.3),
        0 0 40px rgba(5, 217, 232, 0.2),
        inset 0 0 30px rgba(255, 42, 109, 0.05);
    position: relative;
}

body.dark-mode.medium-mode .main-title,
body.dark-mode.medium-mode .screen-title,
body.dark-mode.medium-mode .question-text {
    background: linear-gradient(90deg, #ff2a6d, #05d9e8, #f3ea5f, #ff2a6d);
    background-size: 200% auto;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 800;
    letter-spacing: 2px;
    text-transform: uppercase;
    animation: cyberpunkText 3s linear infinite;
}

@keyframes cyberpunkText {
    0% { background-position: 0% center; }
    100% { background-position: 200% center; }
}

body.dark-mode.medium-mode .option-btn {
    background: rgba(26, 31, 58, 0.6);
    border: 1px solid rgba(255, 42, 109, 0.5);
    color: var(--cyber-cyan);
    font-family: 'Consolas', monospace;
    font-weight: 600;
    position: relative;
    overflow: hidden;
}

body.dark-mode.medium-mode .option-btn::before {
    content: '//';
    color: var(--cyber-pink);
    margin-right: 8px;
    opacity: 0;
    transition: opacity 0.3s;
}

body.dark-mode.medium-mode .option-btn:hover::before {
    opacity: 1;
}

body.dark-mode.medium-mode .option-btn:hover {
    border-color: var(--cyber-cyan);
    background: radial-gradient(circle at center, rgba(5, 217, 232, 0.2), rgba(26, 31, 58, 0.6));
    box-shadow: 
        0 0 25px rgba(5, 217, 232, 0.5),
        inset 0 0 25px rgba(255, 42, 109, 0.2);
}

body.dark-mode.medium-mode .progress-bar {
    background: linear-gradient(90deg, #ff2a6d, #05d9e8, #f3ea5f);
    box-shadow: 0 0 20px rgba(255, 42, 109, 0.6);
    animation: cyberpunkProgress 2s linear infinite;
}

@keyframes cyberpunkProgress {
    0% { filter: hue-rotate(0deg); }
    100% { filter: hue-rotate(360deg); }
}

body.dark-mode.medium-mode .select-btn,
body.dark-mode.medium-mode .nav-btn,
body.dark-mode.medium-mode .submit-btn,
body.dark-mode.medium-mode .restart-btn {
    background: rgba(26, 31, 58, 0.7);
    border: 1px solid var(--cyber-pink);
    color: var(--cyber-cyan);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 2px;
    position: relative;
    overflow: hidden;
}

body.dark-mode.medium-mode .select-btn:hover,
body.dark-mode.medium-mode .nav-btn:hover,
body.dark-mode.medium-mode .submit-btn:hover,
body.dark-mode.medium-mode .restart-btn:hover {
    background: radial-gradient(circle at center, rgba(255, 42, 109, 0.3), rgba(26, 31, 58, 0.7));
    box-shadow: 
        0 0 30px rgba(255, 42, 109, 0.7),
        0 0 50px rgba(5, 217, 232, 0.5),
        inset 0 0 30px rgba(255, 42, 109, 0.3);
    transform: translateY(-2px);
}

body.dark-mode.medium-mode .score-circle {
    background: radial-gradient(circle, #ff2a6d, #05d9e8);
    box-shadow: 
        0 0 50px rgba(255, 42, 109, 0.8),
        0 0 80px rgba(5, 217, 232, 0.6);
    animation: scaleIn 0.6s ease-out, cyberpunkPulse 2s ease-in-out infinite;
}

@keyframes cyberpunkPulse {
    0%, 100% { 
        box-shadow: 0 0 50px rgba(255, 42, 109, 0.8), 0 0 80px rgba(5, 217, 232, 0.6);
    }
    50% { 
        box-shadow: 0 0 70px rgba(5, 217, 232, 0.9), 0 0 100px rgba(255, 42, 109, 0.7);
    }
}

/* Hard Mode - Elite Hacker Terminal */
body.dark-mode.hard-mode {
    --bg-primary: #000000;
    --bg-secondary: #0a0a0a;
    --text-primary: #00ffff;
    --text-secondary: #ff00ff;
    --accent: #00ffff;
    --accent-hover: #ff00ff;
    --cyber-cyan: #00ffff;
    --cyber-magenta: #ff00ff;
    --cyber-yellow: #ffff00;
    --cyber-green: #00ff00;
    font-family: 'Fira Code', 'Consolas', 'Monaco', monospace;
    overflow-x: hidden;
}

body.dark-mode.hard-mode .container {
    background: #000000;
    position: relative;
}

body.dark-mode.hard-mode .container::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        repeating-linear-gradient(0deg, rgba(0, 255, 255, 0.03) 0px, transparent 1px, transparent 2px, rgba(0, 255, 255, 0.03) 3px),
        repeating-linear-gradient(90deg, rgba(255, 0, 255, 0.03) 0px, transparent 1px, transparent 2px, rgba(255, 0, 255, 0.03) 3px);
    background-size: 100px 100px;
    pointer-events: none;
    z-index: 1;
    animation: gridScroll 30s linear infinite;
}

@keyframes gridScroll {
    0% { transform: translate(0, 0); }
    100% { transform: translate(100px, 100px); }
}

/* ===== GLOBAL STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    transition: all var(--transition-speed);
    position: relative;
}

/* Light Mode - Elegant Background */
body:not(.dark-mode) {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
}

body:not(.dark-mode)::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 30%, rgba(74, 144, 226, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 70%, rgba(99, 102, 241, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(139, 92, 246, 0.05) 0%, transparent 70%);
    pointer-events: none;
    z-index: 0;
    animation: lightModeGlow 10s ease-in-out infinite;
}

@keyframes lightModeGlow {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ===== PARTICLE CANVAS (Hard Mode Only) ===== */
#particleCanvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
    opacity: 0;
    transition: opacity 0.5s;
}

body.dark-mode.hard-mode #particleCanvas {
    opacity: 1;
}

/* ===== HEADER ===== */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
    position: relative;
    z-index: 1;
}

.main-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    transition: all var(--transition-speed);
}

/* Hard Mode - Elite Hacker Text */
body.dark-mode.hard-mode .main-title,
body.dark-mode.hard-mode .screen-title,
body.dark-mode.hard-mode .question-text {
    background: linear-gradient(90deg, #00ffff, #ff00ff, #ffff00, #00ff00, #00ffff);
    background-size: 300% auto;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 900;
    letter-spacing: 4px;
    text-transform: uppercase;
    animation: hackerText 4s linear infinite;
    filter: drop-shadow(0 0 10px rgba(0, 255, 255, 0.5));
}

@keyframes hackerText {
    0% { background-position: 0% center; }
    100% { background-position: 300% center; }
}

body.dark-mode.hard-mode .footer-text,
body.dark-mode.hard-mode h3,
body.dark-mode.hard-mode p,
body.dark-mode.hard-mode span:not(.score-value):not(.score-total),
body.dark-mode.hard-mode .analytics-title {
    color: var(--cyber-cyan);
    text-shadow: 0 0 10px rgba(0, 255, 255, 0.5);
}

.theme-btn {
    padding: 10px 20px;
    background: var(--accent);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    transition: all var(--transition-speed);
}

.theme-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
}

/* Hard Mode - Elite Button */
body.dark-mode.hard-mode .theme-btn {
    background: rgba(0, 0, 0, 0.8);
    border: 1px solid var(--cyber-cyan);
    color: var(--cyber-cyan);
    box-shadow: 0 0 15px rgba(0, 255, 255, 0.3);
}

body.dark-mode.hard-mode .theme-btn:hover {
    background: radial-gradient(circle at center, rgba(0, 255, 255, 0.2), rgba(0, 0, 0, 0.8));
    box-shadow: 0 0 30px rgba(0, 255, 255, 0.6), inset 0 0 20px rgba(0, 255, 255, 0.2);
}

/* ===== SCREENS ===== */
.screen {
    display: none;
    flex: 1;
    position: relative;
    z-index: 1;
}

.screen.active {
    display: block;
    animation: fadeIn 0.5s;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.screen-title {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 40px;
    color: var(--text-primary);
}

/* ===== DIFFICULTY CARDS ===== */
.difficulty-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}

.difficulty-card {
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: 30px;
    text-align: center;
    transition: all var(--transition-speed);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

/* Light Mode - Elegant Card Style */
body:not(.dark-mode) .difficulty-card {
    background: white;
    box-shadow: var(--card-shadow);
    border: 1px solid rgba(0, 0, 0, 0.06);
}

body:not(.dark-mode) .difficulty-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(74, 144, 226, 0.05), rgba(99, 102, 241, 0.05));
    opacity: 0;
    transition: opacity 0.3s;
}

body:not(.dark-mode) .difficulty-card:hover::before {
    opacity: 1;
}

body:not(.dark-mode) .difficulty-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 50px rgba(74, 144, 226, 0.2);
}

.difficulty-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px var(--shadow);
}

/* Light Mode - Enhanced Buttons */
body:not(.dark-mode) .select-btn,
body:not(.dark-mode) .nav-btn,
body:not(.dark-mode) .submit-btn,
body:not(.dark-mode) .restart-btn {
    background: linear-gradient(135deg, #4a90e2, #357abd);
    box-shadow: 0 4px 15px rgba(74, 144, 226, 0.3);
}

body:not(.dark-mode) .select-btn:hover,
body:not(.dark-mode) .nav-btn:hover,
body:not(.dark-mode) .submit-btn:hover,
body:not(.dark-mode) .restart-btn:hover {
    box-shadow: 0 6px 20px rgba(74, 144, 226, 0.4);
    transform: translateY(-3px);
}

body:not(.dark-mode) .option-btn {
    background: white;
    border: 2px solid #e9ecef;
    transition: all 0.3s ease;
}

body:not(.dark-mode) .option-btn:hover {
    border-color: #4a90e2;
    background: linear-gradient(135deg, rgba(74, 144, 226, 0.1), rgba(99, 102, 241, 0.1));
    box-shadow: 0 4px 15px rgba(74, 144, 226, 0.2);
}

body:not(.dark-mode) .option-btn.selected {
    background: linear-gradient(135deg, #4a90e2, #357abd);
    border-color: #357abd;
    color: white;
}

body:not(.dark-mode) .progress-bar {
    background: linear-gradient(90deg, #4a90e2, #6366f1);
    box-shadow: 0 2px 10px rgba(74, 144, 226, 0.3);
}

body:not(.dark-mode) .score-circle {
    background: linear-gradient(135deg, #4a90e2, #6366f1);
    box-shadow: 0 15px 50px rgba(74, 144, 226, 0.4);
}

/* Hard Mode - Elite Card Borders */
body.dark-mode.hard-mode .difficulty-card,
body.dark-mode.hard-mode .quiz-header,
body.dark-mode.hard-mode .quiz-content,
body.dark-mode.hard-mode .results-container {
    background: rgba(0, 0, 0, 0.9);
    border: 1px solid var(--cyber-cyan);
    box-shadow: 
        0 0 20px rgba(0, 255, 255, 0.4),
        0 0 40px rgba(255, 0, 255, 0.2),
        inset 0 0 30px rgba(0, 255, 255, 0.05);
    animation: elitePulse 3s ease-in-out infinite;
}

@keyframes elitePulse {
    0%, 100% { 
        border-color: var(--cyber-cyan);
        box-shadow: 
            0 0 20px rgba(0, 255, 255, 0.4),
            0 0 40px rgba(255, 0, 255, 0.2),
            inset 0 0 30px rgba(0, 255, 255, 0.05);
    }
    50% { 
        border-color: var(--cyber-magenta);
        box-shadow: 
            0 0 30px rgba(255, 0, 255, 0.5),
            0 0 50px rgba(0, 255, 255, 0.3),
            inset 0 0 40px rgba(255, 0, 255, 0.08);
    }
}

.card-icon {
    font-size: 3rem;
    margin-bottom: 15px;
}

.difficulty-card h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.difficulty-card p {
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.select-btn {
    padding: 12px 30px;
    background: var(--accent);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all var(--transition-speed);
    width: 100%;
}

.select-btn:hover {
    background: var(--accent-hover);
    transform: scale(1.05);
}

/* Hard Mode - Elite Hover Effects */
body.dark-mode.hard-mode .select-btn,
body.dark-mode.hard-mode .nav-btn,
body.dark-mode.hard-mode .submit-btn,
body.dark-mode.hard-mode .restart-btn {
    background: rgba(0, 0, 0, 0.8);
    border: 1px solid var(--cyber-cyan);
    color: var(--cyber-cyan);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 3px;
}

body.dark-mode.hard-mode .select-btn:hover,
body.dark-mode.hard-mode .nav-btn:hover,
body.dark-mode.hard-mode .submit-btn:hover,
body.dark-mode.hard-mode .restart-btn:hover {
    background: radial-gradient(circle at center, rgba(0, 255, 255, 0.3), rgba(0, 0, 0, 0.8));
    box-shadow: 
        0 0 40px rgba(0, 255, 255, 0.7),
        0 0 60px rgba(255, 0, 255, 0.5),
        inset 0 0 40px rgba(0, 255, 255, 0.3);
    border-color: var(--cyber-magenta);
    transform: translateY(-2px);
}

body.dark-mode.hard-mode .option-btn {
    background: rgba(0, 0, 0, 0.7);
    border: 1px solid rgba(0, 255, 255, 0.5);
    color: var(--cyber-cyan);
    font-family: 'Consolas', monospace;
}

body.dark-mode.hard-mode .option-btn::before {
    content: '$ ';
    color: var(--cyber-magenta);
    opacity: 0;
    transition: opacity 0.3s;
}

body.dark-mode.hard-mode .option-btn:hover::before {
    opacity: 1;
}

body.dark-mode.hard-mode .option-btn:hover {
    background: radial-gradient(circle at center, rgba(0, 255, 255, 0.2), rgba(0, 0, 0, 0.7));
    box-shadow: 
        0 0 30px rgba(0, 255, 255, 0.5),
        inset 0 0 30px rgba(255, 0, 255, 0.2);
    border-color: var(--cyber-magenta);
    transform: translateX(10px);
}

/* ===== QUIZ SCREEN ===== */
.quiz-header {
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 30px;
}

/* Light Mode - Elegant Quiz Header */
body:not(.dark-mode) .quiz-header {
    background: white;
    box-shadow: var(--card-shadow);
    border: 1px solid rgba(0, 0, 0, 0.06);
}

body.dark-mode.hard-mode .quiz-header {
    background: linear-gradient(135deg, rgba(15, 20, 25, 0.9), rgba(10, 14, 26, 0.95));
    border: 1px solid rgba(6, 182, 212, 0.4);
    box-shadow: 0 0 30px rgba(6, 182, 212, 0.2), inset 0 0 30px rgba(6, 182, 212, 0.05);
}

.quiz-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.difficulty-badge {
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    text-transform: uppercase;
}

.difficulty-badge.easy { background: #27ae60; color: white; }
.difficulty-badge.medium { background: #f39c12; color: white; }
.difficulty-badge.hard { background: #e74c3c; color: white; }

.timer {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.progress-container {
    width: 100%;
    height: 8px;
    background: var(--border);
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 10px;
}

.progress-bar {
    height: 100%;
    background: var(--accent);
    border-radius: 10px;
    transition: width 0.3s ease;
}

/* Hard Mode - Elite Progress Bar */
body.dark-mode.hard-mode .progress-bar {
    background: linear-gradient(90deg, #00ffff, #ff00ff, #ffff00, #00ff00);
    background-size: 200% auto;
    box-shadow: 0 0 20px rgba(0, 255, 255, 0.6);
    animation: eliteProgress 2s linear infinite;
}

@keyframes eliteProgress {
    0% { 
        background-position: 0% center;
        box-shadow: 0 0 20px rgba(0, 255, 255, 0.6);
    }
    50% {
        box-shadow: 0 0 30px rgba(255, 0, 255, 0.8);
    }
    100% { 
        background-position: 200% center;
        box-shadow: 0 0 20px rgba(0, 255, 255, 0.6);
    }
}

.question-counter {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.quiz-content {
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 12px;
    padding: 30px;
    margin-bottom: 30px;
}

/* Light Mode - Elegant Quiz Content */
body:not(.dark-mode) .quiz-content {
    background: white;
    box-shadow: var(--card-shadow);
    border: 1px solid rgba(0, 0, 0, 0.06);
}

body.dark-mode.hard-mode .quiz-content {
    background: linear-gradient(135deg, rgba(15, 20, 25, 0.9), rgba(10, 14, 26, 0.95));
    border: 1px solid rgba(6, 182, 212, 0.4);
    box-shadow: 0 0 30px rgba(6, 182, 212, 0.2), inset 0 0 30px rgba(6, 182, 212, 0.05);
}

.question-text {
    font-size: 1.5rem;
    margin-bottom: 30px;
    line-height: 1.6;
    color: var(--text-primary);
}

.options-container {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.option-btn {
    padding: 15px 20px;
    background: var(--bg-primary);
    border: 2px solid var(--border);
    border-radius: 10px;
    cursor: pointer;
    font-size: 1rem;
    text-align: left;
    transition: all var(--transition-speed);
    color: var(--text-primary);
}

.option-btn:hover {
    border-color: var(--accent);
    background: var(--accent);
    color: white;
    transform: translateX(10px);
}

.option-btn.selected {
    border-color: var(--accent);
    background: var(--accent);
    color: white;
}

.option-btn.correct {
    border-color: #27ae60;
    background: #27ae60;
    color: white;
}

.option-btn.incorrect {
    border-color: #e74c3c;
    background: #e74c3c;
    color: white;
}

body.dark-mode.hard-mode .option-btn {
    background: linear-gradient(135deg, rgba(15, 20, 25, 0.6), rgba(10, 14, 26, 0.8));
    border: 1px solid rgba(6, 182, 212, 0.3);
    box-shadow: 0 0 15px rgba(6, 182, 212, 0.1);
}

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

.nav-btn, .submit-btn {
    padding: 12px 30px;
    background: var(--accent);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all var(--transition-speed);
}

.nav-btn:hover:not(:disabled), .submit-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
}

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

.submit-btn {
    flex: 1;
    background: #27ae60;
}

.submit-btn:hover {
    background: #229954;
}

body.dark-mode.hard-mode .nav-btn,
body.dark-mode.hard-mode .submit-btn {
    background: linear-gradient(135deg, rgba(6, 182, 212, 0.2), rgba(20, 184, 166, 0.2));
    border: 1px solid rgba(6, 182, 212, 0.5);
    box-shadow: 0 0 20px rgba(6, 182, 212, 0.2);
}

/* ===== RESULTS SCREEN ===== */
.results-container {
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: 40px;
    text-align: center;
}

/* Light Mode - Elegant Results */
body:not(.dark-mode) .results-container {
    background: white;
    box-shadow: var(--card-shadow);
    border: 1px solid rgba(0, 0, 0, 0.06);
}

body.dark-mode.hard-mode .results-container {
    background: linear-gradient(135deg, rgba(15, 20, 25, 0.9), rgba(10, 14, 26, 0.95));
    border: 1px solid rgba(6, 182, 212, 0.4);
    box-shadow: 0 0 40px rgba(6, 182, 212, 0.3), inset 0 0 40px rgba(6, 182, 212, 0.05);
}

.score-display {
    margin-bottom: 40px;
}

.score-circle {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: var(--accent);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    box-shadow: 0 10px 40px var(--shadow);
    animation: scaleIn 0.6s ease-out;
}

@keyframes scaleIn {
    from { transform: scale(0); }
    to { transform: scale(1); }
}

body.dark-mode.hard-mode .score-circle {
    background: radial-gradient(circle, #00ffff, #ff00ff, #000000);
    animation: scaleIn 0.6s ease-out, eliteScorePulse 2s ease-in-out infinite;
}

@keyframes eliteScorePulse {
    0%, 100% { 
        box-shadow: 
            0 0 50px rgba(0, 255, 255, 0.8),
            0 0 80px rgba(255, 0, 255, 0.6);
    }
    50% { 
        box-shadow: 
            0 0 70px rgba(255, 0, 255, 0.9),
            0 0 100px rgba(0, 255, 255, 0.7);
    }
}

.score-value {
    font-size: 4rem;
    font-weight: 700;
    color: white;
}

.score-total {
    font-size: 1.5rem;
    color: rgba(255, 255, 255, 0.8);
}

.performance-badge {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 30px;
    font-size: 1.3rem;
    font-weight: 700;
    text-transform: uppercase;
    animation: bounceIn 0.8s ease-out;
}

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

.performance-badge.beginner {
    background: linear-gradient(135deg, #f39c12, #e67e22);
    color: white;
}

.performance-badge.intermediate {
    background: linear-gradient(135deg, #3498db, #2980b9);
    color: white;
}

.performance-badge.advanced {
    background: linear-gradient(135deg, #27ae60, #229954);
    color: white;
}

body.dark-mode.hard-mode .performance-badge {
    animation: bounceIn 0.8s ease-out;
    box-shadow: 0 0 30px rgba(6, 182, 212, 0.4);
    border: 1px solid rgba(6, 182, 212, 0.5);
}

.analytics {
    margin-bottom: 30px;
}

.analytics-title {
    font-size: 1.5rem;
    margin-bottom: 20px;
    color: var(--text-primary);
}

.analytics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.analytics-item {
    background: var(--bg-primary);
    border: 2px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    transition: all var(--transition-speed);
}

.analytics-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 20px var(--shadow);
}

body.dark-mode.hard-mode .analytics-item {
    background: rgba(0, 0, 0, 0.8);
    border: 1px solid var(--cyber-cyan);
    box-shadow: 0 0 15px rgba(0, 255, 255, 0.3);
}

body.dark-mode.hard-mode .analytics-item:hover {
    box-shadow: 0 0 25px rgba(255, 0, 255, 0.5);
    border-color: var(--cyber-magenta);
}

body.dark-mode.hard-mode .analytics-value {
    color: var(--cyber-magenta);
    text-shadow: 0 0 10px var(--cyber-magenta);
}

/* Medium Mode Analytics */
body.dark-mode.medium-mode .analytics-item {
    background: rgba(26, 31, 58, 0.7);
    border: 1px solid var(--cyber-pink);
    box-shadow: 0 0 15px rgba(255, 42, 109, 0.3);
}

body.dark-mode.medium-mode .analytics-item:hover {
    box-shadow: 0 0 25px rgba(5, 217, 232, 0.5);
    border-color: var(--cyber-cyan);
}

body.dark-mode.medium-mode .analytics-value {
    color: var(--cyber-cyan);
    text-shadow: 0 0 10px var(--cyber-cyan);
}

/* Easy Mode Analytics */
body.dark-mode.easy-mode .analytics-item {
    background: rgba(0, 59, 0, 0.4);
    border: 1px solid var(--matrix-green);
    box-shadow: 0 0 10px rgba(0, 255, 65, 0.3);
}

body.dark-mode.easy-mode .analytics-item:hover {
    box-shadow: 0 0 20px rgba(0, 255, 65, 0.5);
}

body.dark-mode.easy-mode .analytics-value {
    color: var(--matrix-green);
    text-shadow: 0 0 10px var(--matrix-green);
}

.analytics-label {
    display: block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.analytics-value {
    display: block;
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--accent);
}

.restart-btn {
    padding: 15px 40px;
    background: var(--accent);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.1rem;
    font-weight: 600;
    transition: all var(--transition-speed);
}

.restart-btn:hover {
    background: var(--accent-hover);
    transform: scale(1.05);
}

body.dark-mode.hard-mode .restart-btn {
    background: linear-gradient(135deg, rgba(6, 182, 212, 0.2), rgba(20, 184, 166, 0.2));
    border: 1px solid rgba(6, 182, 212, 0.5);
    box-shadow: 0 0 25px rgba(6, 182, 212, 0.3);
}

/* ===== FOOTER ===== */
.footer {
    text-align: center;
    padding: 20px 0;
    margin-top: auto;
    position: relative;
    z-index: 1;
}

.footer-text {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 768px) {
    .main-title {
        font-size: 2rem;
    }
    
    .difficulty-cards {
        grid-template-columns: 1fr;
    }
    
    .quiz-footer {
        flex-direction: column;
    }
    
    .analytics-grid {
        grid-template-columns: 1fr;
    }
    
    .score-circle {
        width: 150px;
        height: 150px;
    }
    
    .score-value {
        font-size: 3rem;
    }
}

/* ===== MOBILE OPTIMIZATIONS ===== */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
    
    .main-title {
        font-size: 1.8rem;
    }
    
    .screen-title {
        font-size: 1.5rem;
    }
    
    .difficulty-cards {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .quiz-footer {
        flex-direction: column;
    }
    
    .nav-btn, .submit-btn {
        width: 100%;
    }
    
    .analytics-grid {
        grid-template-columns: 1fr 1fr;
        gap: 15px;
    }
    
    .score-circle {
        width: 150px;
        height: 150px;
    }
    
    .score-value {
        font-size: 3rem;
    }
    
    .question-text {
        font-size: 1.2rem;
    }
    
    .option-btn {
        padding: 12px 15px;
        font-size: 0.95rem;
    }
    
    .review-item {
        padding: 15px;
    }
    
    .review-question {
        font-size: 1rem;
    }
}

/* ===== TOUCH FEEDBACK FOR MOBILE ===== */
@media (hover: none) and (pointer: coarse) {
    .option-btn:active,
    .select-btn:active,
    .nav-btn:active,
    .submit-btn:active,
    .restart-btn:active,
    .theme-btn:active {
        transform: scale(0.95);
        transition: transform 0.1s;
    }
    
    .difficulty-card:active {
        transform: scale(0.98);
    }
}

/* ===== SWIPE INDICATOR (Mobile) ===== */
.swipe-indicator {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 10px 20px;
    border-radius: 20px;
    font-size: 0.9rem;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
}

.swipe-indicator.show {
    opacity: 1;
}

@media (min-width: 769px) {
    .swipe-indicator {
        display: none;
    }
}

/* ===== KEYBOARD NAVIGATION HINT ===== */
.keyboard-hint {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 15px 20px;
    border-radius: 12px;
    font-size: 0.85rem;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
    max-width: 250px;
}

.keyboard-hint.show {
    opacity: 1;
}

.keyboard-hint kbd {
    background: rgba(255, 255, 255, 0.2);
    padding: 3px 8px;
    border-radius: 4px;
    font-family: monospace;
    font-size: 0.9rem;
    margin: 0 2px;
}

@media (max-width: 768px) {
    .keyboard-hint {
        display: none;
    }
}

/* ===== LOADING ANIMATION ===== */
@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.loading {
    animation: pulse 1.5s ease-in-out infinite;
}

/* ===== ACCESSIBILITY ===== */
.option-btn:focus,
.select-btn:focus,
.nav-btn:focus,
.submit-btn:focus,
.restart-btn:focus,
.theme-btn:focus {
    outline: 3px solid var(--accent);
    outline-offset: 2px;
}

/* ===== SMOOTH SCROLLING ===== */
html {
    scroll-behavior: smooth;
}

/* ===== SELECTION COLORS ===== */
::selection {
    background: var(--accent);
    color: white;
}

::-moz-selection {
    background: var(--accent);
    color: white;
}