/* ============================================
   Mnemo.space - Modern Mobile-First Styles
   ============================================ */

:root {
    /* Color Palette */
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #ec4899;
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;

    /* Neutrals */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-card: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --border: #475569;

    /* Shadows & Effects */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --glow: 0 0 20px rgba(99, 102, 241, 0.5);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* Typography */
    --font-base: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-display: 'Trebuchet MS', 'Lucida Grande', sans-serif;
}

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

html, body {
    height: 100%;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-base);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    position: relative;
}

/* ============================================
   Particles Background with 3D Effect
   ============================================ */

.particles-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
    background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    overflow: hidden;
    transition: background 0.5s ease;
    perspective: 1000px;
    transform-style: preserve-3d;
}

.particles-bg.practice-mode {
    background: linear-gradient(135deg, #4a0e29 0%, #701a49 100%);
}

/* Layer 1 - Far background */
.particles-bg::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background-image:
        radial-gradient(circle, rgba(99, 102, 241, 0.05) 2px, transparent 2px),
        radial-gradient(circle, rgba(236, 72, 153, 0.05) 2px, transparent 2px);
    background-size: 100px 100px, 150px 150px;
    background-position: 0 0, 75px 75px;
    animation: particlesFloatFar 90s linear infinite;
    transition: background-image 0.5s ease;
    transform: translateZ(-200px) scale(1.5);
    opacity: 0.4;
}

/* Layer 2 - Middle layer */
.particles-bg::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background-image:
        radial-gradient(circle, rgba(99, 102, 241, 0.15) 1.5px, transparent 1.5px),
        radial-gradient(circle, rgba(236, 72, 153, 0.15) 1.5px, transparent 1.5px);
    background-size: 60px 60px, 90px 90px;
    background-position: 0 0, 45px 45px;
    animation: particlesFloatMid 60s linear infinite;
    transition: background-image 0.5s ease;
    transform: translateZ(-100px) scale(1.3);
    opacity: 0.6;
}

.particles-bg.practice-mode::before,
.particles-bg.practice-mode::after {
    background-image:
        radial-gradient(circle, rgba(236, 72, 153, 0.15) 2px, transparent 2px),
        radial-gradient(circle, rgba(219, 39, 119, 0.15) 2px, transparent 2px);
}

@keyframes particlesFloatFar {
    0% { transform: translateZ(-200px) scale(1.5) translate(0, 0); }
    100% { transform: translateZ(-200px) scale(1.5) translate(100px, 100px); }
}

@keyframes particlesFloatMid {
    0% { transform: translateZ(-100px) scale(1.3) translate(0, 0); }
    100% { transform: translateZ(-100px) scale(1.3) translate(60px, 60px); }
}

/* ============================================
   App Container
   ============================================ */

.app-container {
    position: relative;
    z-index: 1;
    height: 100vh;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
}

/* ============================================
   Screen Management
   ============================================ */

.screen {
    display: none;
    min-height: 100vh;
    padding: var(--spacing-md);
    animation: fadeIn 0.3s ease-in-out;
}

.screen.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ============================================
   Header
   ============================================ */

.header {
    text-align: center;
    padding: var(--spacing-lg) 0;
}

.header h1 {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-light), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
    animation: titleBounce 2s ease-in-out infinite;
}

@keyframes titleBounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-5px); }
}

.tagline {
    color: var(--text-secondary);
    font-size: 1rem;
    margin-top: var(--spacing-xs);
}

/* ============================================
   Buttons
   ============================================ */

.btn {
    padding: var(--spacing-sm) var(--spacing-md);
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
    font-family: var(--font-base);
    outline: none;
    touch-action: manipulation;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
}

.btn-primary:hover, .btn-primary:active {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md), var(--glow);
}

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

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

.btn-large {
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: 1.2rem;
    width: 100%;
    max-width: 400px;
}

.btn-small {
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.9rem;
}

/* ============================================
   Series List
   ============================================ */

.series-list {
    margin: var(--spacing-lg) 0;
}

.series-list h2 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.series-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.series-card {
    background: var(--bg-card);
    border-radius: 16px;
    padding: var(--spacing-md);
    box-shadow:
        var(--shadow-md),
        0 10px 30px rgba(0, 0, 0, 0.3);
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    border: 2px solid transparent;
    position: relative;
    overflow: hidden;
    transform-style: preserve-3d;
    transform: perspective(1000px) translateZ(0);
}

.series-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transform: translateZ(10px);
}

.series-card:hover, .series-card:active {
    transform: perspective(1000px) translateY(-8px) translateZ(30px);
    border-color: var(--primary);
    box-shadow:
        var(--shadow-lg),
        0 20px 50px rgba(99, 102, 241, 0.4),
        0 0 20px rgba(99, 102, 241, 0.2);
}

.series-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-sm);
}

.series-card-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-primary);
}

.series-card-delete {
    background: var(--error);
    color: white;
    border: none;
    padding: 0.4rem 0.8rem;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s ease;
}

.series-card-delete:hover {
    background: #dc2626;
    transform: scale(1.05);
}

.series-card-meta {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
}

.series-card-meta span {
    margin-right: var(--spacing-sm);
}

.series-card-actions {
    display: flex;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
}

.series-card-btn {
    flex: 1;
    padding: var(--spacing-xs) var(--spacing-sm);
    border: none;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.series-card-btn-play {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
}

.series-card-btn-practice {
    background: linear-gradient(135deg, #ec4899, #db2777);
    color: white;
}

.series-card-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

/* ============================================
   High Scores
   ============================================ */

.high-scores {
    margin: var(--spacing-xl) 0;
}

.high-scores h2 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-md);
}

.scores-list {
    background: var(--bg-card);
    border-radius: 16px;
    padding: var(--spacing-md);
    box-shadow: var(--shadow-md);
}

.score-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm);
    border-bottom: 1px solid var(--border);
}

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

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

.score-value {
    color: var(--secondary);
    font-weight: 700;
    font-size: 1.1rem;
}

.no-scores {
    text-align: center;
    color: var(--text-secondary);
    padding: var(--spacing-md);
}

/* ============================================
   Form Container
   ============================================ */

.form-container {
    max-width: 600px;
    margin: 0 auto;
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.form-group {
    margin-bottom: var(--spacing-md);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
    color: var(--text-primary);
}

.form-group input {
    width: 100%;
    padding: var(--spacing-sm);
    border: 2px solid var(--border);
    border-radius: 8px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
    font-family: var(--font-base);
    outline: none;
    transition: all 0.3s ease;
}

.form-group input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.cards-container {
    margin-bottom: var(--spacing-sm);
}

.card-input-group {
    background: var(--bg-secondary);
    padding: var(--spacing-sm);
    border-radius: 8px;
    margin-bottom: var(--spacing-sm);
    border: 2px solid var(--border);
}

.card-input-group input {
    margin-bottom: var(--spacing-xs);
}

.card-input-remove {
    background: var(--error);
    color: white;
    border: none;
    padding: 0.3rem 0.6rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.85rem;
}

.form-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

.form-actions .btn {
    flex: 1;
}

/* ============================================
   Game Options
   ============================================ */

.form-group label input[type="checkbox"] {
    width: auto;
    margin-right: var(--spacing-xs);
    cursor: pointer;
}

.form-group input[type="range"] {
    width: 100%;
    height: 8px;
    background: var(--bg-secondary);
    border-radius: 4px;
    outline: none;
    -webkit-appearance: none;
    appearance: none;
}

.form-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    cursor: pointer;
    border-radius: 50%;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.form-group input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
    box-shadow: var(--shadow-md);
}

.form-group input[type="range"]::-moz-range-thumb {
    width: 24px;
    height: 24px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    cursor: pointer;
    border-radius: 50%;
    border: none;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.form-group input[type="range"]::-moz-range-thumb:hover {
    transform: scale(1.2);
    box-shadow: var(--shadow-md);
}

.difficulty-labels {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: var(--spacing-xs);
    padding: 0 var(--spacing-xs);
}

.hint {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-top: var(--spacing-xs);
    font-style: italic;
}

/* ============================================
   Game Screen
   ============================================ */

.game-header {
    background: var(--bg-card);
    padding: var(--spacing-sm);
    border-radius: 12px;
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow-md);
}

.game-info {
    margin-top: var(--spacing-sm);
}

.series-name {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--bg-secondary);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: var(--spacing-sm);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transition: width 0.5s ease;
    width: 0%;
}

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

/* ============================================
   Game Content
   ============================================ */

.game-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: calc(100vh - 180px);
}

.timer-display {
    margin-bottom: var(--spacing-lg);
    animation: pulseGlow 2s ease-in-out infinite;
}

.timer-display.hidden {
    display: none;
}

@keyframes pulseGlow {
    0%, 100% { opacity: 0.8; }
    50% { opacity: 1; }
}

.timer-circle {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--warning), #f97316);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg), 0 0 30px rgba(245, 158, 11, 0.5);
    animation: timerSpin 1s linear infinite;
}

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

.timer-circle span {
    font-size: 2rem;
    font-weight: 800;
    color: white;
}

/* ============================================
   Card Display with 3D Effects
   ============================================ */

.card-display {
    width: 100%;
    max-width: 500px;
    margin: 0 auto var(--spacing-lg);
    perspective: 1500px;
    transform-style: preserve-3d;
}

.card-front {
    background: linear-gradient(135deg, var(--bg-card), var(--bg-secondary));
    border-radius: 20px;
    padding: var(--spacing-xl);
    box-shadow:
        var(--shadow-lg),
        0 20px 60px rgba(0, 0, 0, 0.4),
        0 0 0 1px rgba(99, 102, 241, 0.1);
    border: 3px solid var(--primary);
    min-height: 300px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    animation: cardFlip 0.6s ease-in-out;
    transform-style: preserve-3d;
    transition: transform 0.3s ease;
    position: relative;
}

.card-front::before {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.2), rgba(236, 72, 153, 0.2));
    border-radius: 20px;
    z-index: -1;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.card-front:hover::before {
    opacity: 1;
}

@keyframes cardFlip {
    0% {
        transform: rotateY(90deg) translateZ(0);
        opacity: 0;
    }
    100% {
        transform: rotateY(0deg) translateZ(50px);
        opacity: 1;
    }
}

.card-emoji {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
    animation: bounceIn 0.8s ease-in-out;
}

@keyframes bounceIn {
    0% { transform: scale(0); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

.card-question {
    font-size: 1.8rem;
    font-weight: 700;
    text-align: center;
    color: var(--text-primary);
    line-height: 1.4;
}

/* ============================================
   Answer Section
   ============================================ */

.answer-section {
    width: 100%;
    max-width: 500px;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    animation: slideUp 0.4s ease-in-out;
}

.answer-section.hidden {
    display: none;
}

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

.answer-input {
    width: 100%;
    padding: var(--spacing-md);
    font-size: 1.2rem;
    border: 3px solid var(--primary);
    border-radius: 12px;
    background: var(--bg-card);
    color: var(--text-primary);
    text-align: center;
    font-weight: 600;
    outline: none;
    transition: all 0.3s ease;
}

.answer-input:focus {
    border-color: var(--secondary);
    box-shadow: 0 0 0 4px rgba(236, 72, 153, 0.3);
}

/* ============================================
   Result Feedback with 3D
   ============================================ */

.result-feedback {
    width: 100%;
    max-width: 500px;
    animation: zoomIn 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    perspective: 1000px;
    transform-style: preserve-3d;
}

.result-feedback.hidden {
    display: none;
}

@keyframes zoomIn {
    from {
        transform: scale(0) translateZ(-100px);
        opacity: 0;
    }
    to {
        transform: scale(1) translateZ(30px);
        opacity: 1;
    }
}

.feedback-content {
    background: var(--bg-card);
    border-radius: 20px;
    padding: var(--spacing-xl);
    text-align: center;
    box-shadow:
        var(--shadow-lg),
        0 15px 40px rgba(0, 0, 0, 0.4);
    margin-bottom: var(--spacing-md);
    transform: translateZ(20px);
    transition: transform 0.3s ease;
}

.feedback-content:hover {
    transform: translateZ(40px);
}

.feedback-emoji {
    font-size: 5rem;
    margin-bottom: var(--spacing-md);
    animation: spin 0.8s ease-in-out;
}

@keyframes spin {
    0% { transform: rotate(0deg) scale(0); }
    50% { transform: rotate(180deg) scale(1.2); }
    100% { transform: rotate(360deg) scale(1); }
}

.feedback-message {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.feedback-answer {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-top: var(--spacing-sm);
}

.feedback-correct {
    color: var(--success);
}

.feedback-incorrect {
    color: var(--error);
}

/* ============================================
   Game Complete with 3D
   ============================================ */

.game-complete {
    width: 100%;
    max-width: 600px;
    animation: celebrationBounce 1s ease-in-out;
    perspective: 1000px;
    transform-style: preserve-3d;
}

.game-complete.hidden {
    display: none;
}

@keyframes celebrationBounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0) translateZ(0); }
    40% { transform: translateY(-30px) translateZ(50px); }
    60% { transform: translateY(-15px) translateZ(30px); }
}

.complete-content {
    background: linear-gradient(135deg, var(--bg-card), var(--bg-secondary));
    border-radius: 20px;
    padding: var(--spacing-xl);
    text-align: center;
    box-shadow:
        var(--shadow-lg),
        0 25px 50px rgba(0, 0, 0, 0.5),
        0 0 0 1px rgba(16, 185, 129, 0.3);
    border: 3px solid var(--success);
    transform: translateZ(30px);
    transform-style: preserve-3d;
    transition: transform 0.3s ease;
}

.complete-content:hover {
    transform: translateZ(50px) scale(1.02);
}

.complete-emoji {
    font-size: 6rem;
    margin-bottom: var(--spacing-md);
    animation: confetti 1.5s ease-in-out infinite;
}

@keyframes confetti {
    0%, 100% { transform: rotate(-10deg); }
    50% { transform: rotate(10deg); }
}

.complete-content h2 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(135deg, var(--success), var(--primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.complete-stats {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 2;
}

.complete-score {
    font-size: 2rem;
    font-weight: 800;
    color: var(--secondary);
    margin-bottom: var(--spacing-lg);
}

.complete-actions {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

/* ============================================
   Mobile Optimizations
   ============================================ */

@media (max-width: 768px) {
    .header h1 {
        font-size: 2rem;
    }

    .card-question {
        font-size: 1.4rem;
    }

    .card-emoji {
        font-size: 3rem;
    }

    .form-container {
        padding: var(--spacing-md);
    }

    .series-cards {
        grid-template-columns: 1fr;
    }

    .complete-emoji {
        font-size: 4rem;
    }

    .complete-content h2 {
        font-size: 2rem;
    }
}

/* ============================================
   Keyboard Hints
   ============================================ */

.keyboard-hint {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-top: var(--spacing-sm);
    opacity: 0.7;
    font-style: italic;
}

/* ============================================
   Utility Classes
   ============================================ */

.hidden {
    display: none !important;
}

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

.shake {
    animation: shake 0.5s;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    10%, 30%, 50%, 70%, 90% { transform: translateX(-10px); }
    20%, 40%, 60%, 80% { transform: translateX(10px); }
}

.pulse {
    animation: pulse 0.5s;
}

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