/* ============================================================
   Quantum Experience — SCIUS BUU
   Stylesheet: "Artistic Indie" design language
   Dark cinematic mode with warm accents (amber, coral, soft purple)
   ============================================================ */

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

:root {
    --bg-deep: #0B0D14;
    --bg-mid: #13151E;
    --bg-card: #1A1B24;
    --glass: rgba(26, 27, 36, 0.85);
    --coral: #E87979;
    --coral-soft: rgba(232, 121, 121, 0.15);
    --gold: #D4A574;
    --gold-soft: rgba(212, 165, 116, 0.15);
    --purple: #8B6BAE;
    --purple-soft: rgba(139, 107, 174, 0.15);
    --text: #E6E2DC;
    --text-secondary: #A8A5A0;
    --text-dim: #6B6966;
    --success: #7CB98B;
    --error: #E87979;
    --border: #2A2B34;
    --glow-coral: rgba(232, 121, 121, 0.25);
    --glow-gold: rgba(212, 165, 116, 0.25);
    --glow-purple: rgba(139, 107, 174, 0.20);
    --font-display: 'Orbitron', 'Kanit', sans-serif;
    --font-body: 'Inter', 'Kanit', sans-serif;
    --font-thai: 'Kanit', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    --radius-lg: 20px;
    --radius-md: 14px;
    --radius-sm: 8px;
}

html { scroll-behavior: smooth; }

html[lang="th"] body { font-family: var(--font-thai), var(--font-body); font-weight: 400; }
html[lang="th"] .quiz-question,
html[lang="th"] .topic-header-desc,
html[lang="th"] .hero-subtitle,
html[lang="th"] .topic-desc,
html[lang="th"] .challenge-strip { font-family: var(--font-thai); font-weight: 400; }
html[lang="th"] .topic-title,
html[lang="th"] .topic-header-title { font-family: var(--font-thai); font-weight: 500; }
html[lang="th"] .btn,
html[lang="th"] .quiz-option,
html[lang="th"] .control-label { font-family: var(--font-thai); font-weight: 500; }

body {
    font-family: var(--font-body);
    background: var(--bg-deep);
    color: var(--text);
    min-height: 100vh;
    overflow-x: hidden;
    line-height: 1.7;
    font-size: 18px;
    letter-spacing: 0.01em;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Warm cosmic background layers */
.bg-cosmos {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    background:
        radial-gradient(1200px 700px at 15% -10%, rgba(212, 165, 116, 0.08), transparent 60%),
        radial-gradient(1000px 800px at 100% 0%, rgba(139, 107, 174, 0.06), transparent 55%),
        radial-gradient(900px 900px at 50% 120%, rgba(232, 121, 121, 0.04), transparent 55%),
        var(--bg-deep);
}

.bg-particles {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 0;
    overflow: hidden;
}

.bg-particle {
    position: absolute;
    width: 4px;
    height: 4px;
    border-radius: 50%;
    opacity: 0.25;
    filter: blur(0.4px);
    animation: drift 22s infinite ease-in-out;
}

@keyframes drift {
    0%, 100% { transform: translateY(0) translateX(0); opacity: 0.2; }
    25% { transform: translateY(-90px) translateX(40px); opacity: 0.5; }
    50% { transform: translateY(-40px) translateX(-30px); opacity: 0.3; }
    75% { transform: translateY(-130px) translateX(18px); opacity: 0.45; }
}

/* ============================================================
   Header
   ============================================================ */
header {
    position: fixed;
    top: 0; left: 0; right: 0;
    height: 66px;
    background: var(--glass);
    backdrop-filter: blur(22px) saturate(140%);
    -webkit-backdrop-filter: blur(22px) saturate(140%);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
    /* Respect notch/safe-area on landscape + notched phones (viewport-fit=cover) */
    padding: 0 calc(clamp(16px, 3vw, 32px) + env(safe-area-inset-right)) 0 calc(clamp(16px, 3vw, 32px) + env(safe-area-inset-left));
    gap: 16px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: var(--text);
    cursor: pointer;
    background: none;
    border: none;
    flex-shrink: 0;
}

.logo-icon, .header-logo-img {
    width: 42px;
    height: 42px;
    border-radius: 12px;
    box-shadow: 0 0 18px var(--glow-gold);
    object-fit: contain;
    background: var(--gold-soft);
    padding: 4px;
}

.logo-text {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 1rem;
    letter-spacing: 1.5px;
    white-space: nowrap;
    color: var(--text);
}

.header-center {
    font-family: var(--font-display);
    font-size: 0.88rem;
    font-weight: 500;
    color: var(--text);
    letter-spacing: 1.5px;
    text-align: center;
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    opacity: 0.85;
}

.header-controls {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-shrink: 0;
}

.toggle-btn {
    height: 44px;
    min-width: 44px;
    padding: 0 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: rgba(255, 255, 255, 0.03);
    color: var(--text);
    cursor: pointer;
    display: grid;
    place-items: center;
    transition: all 0.2s ease;
}

.toggle-btn:hover {
    border-color: var(--coral);
    box-shadow: 0 0 16px var(--glow-coral);
    background: var(--coral-soft);
}

.toggle-btn.active {
    background: linear-gradient(135deg, var(--coral-soft), var(--purple-soft));
    border-color: rgba(232, 121, 121, 0.5);
    color: var(--coral);
}

/* Icons render at full strength (the button already carries opacity via bg) */
.toggle-btn svg { width: 22px; height: 22px; opacity: 1; color: var(--text); }
.toggle-btn.active svg { color: var(--coral); }

.lang-btn {
    font-family: var(--font-display);
    font-size: 0.84rem;
    font-weight: 700;
    letter-spacing: 1.5px;
    color: var(--text);
    opacity: 1;
    transition: color 0.2s, opacity 0.2s;
}

.lang-btn:hover { opacity: 1; color: var(--coral); }

/* ============================================================
   Layout
   ============================================================ */
main {
    position: relative;
    z-index: 1;
    padding-top: 66px;
}

.page { display: none; }
.page.active {
    display: block;
    animation: pageIn 0.5s cubic-bezier(0.22, 1, 0.36, 1);
}

@keyframes pageIn {
    from { opacity: 0; transform: translateY(18px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ============================================================
   Home / Hero Section
   ============================================================ */
.home-hero {
    min-height: calc(100vh - 66px);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 56px 24px 80px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

/* Hero background image */
.hero-bg {
    position: absolute;
    inset: 0;
    z-index: -1;
    background-image: url('https://d8j0ntlcm91z4.cloudfront.net/user_3GoMLVnG8OtCKYFji8KiOMERBWu/hf_20260722_100048_b2f46e8f-0a46-49f6-aa19-a6ac74226734.png');
    background-size: cover;
    background-position: center;
    opacity: 0.35;
    filter: saturate(0.8) brightness(0.6);
}

.hero-bg::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(
        to bottom,
        rgba(11, 13, 20, 0.7) 0%,
        rgba(11, 13, 20, 0.5) 40%,
        rgba(11, 13, 20, 0.8) 70%,
        rgba(11, 13, 20, 1) 100%
    );
}

.hero-glow {
    position: absolute;
    top: 8%;
    left: 50%;
    transform: translateX(-50%);
    width: min(680px, 90vw);
    height: 360px;
    background: radial-gradient(ellipse at center, rgba(212, 165, 116, 0.12), transparent 70%);
    pointer-events: none;
    filter: blur(30px);
}

.hero-glow-warm {
    position: absolute;
    bottom: 20%;
    left: 20%;
    width: 500px;
    height: 400px;
    background: radial-gradient(ellipse at center, rgba(232, 121, 121, 0.08), transparent 70%);
    pointer-events: none;
    filter: blur(40px);
    animation: gentlePulse 8s ease-in-out infinite;
}

@keyframes gentlePulse {
    0%, 100% { opacity: 0.6; transform: scale(1); }
    50% { opacity: 1; transform: scale(1.05); }
}

.eyebrow {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    letter-spacing: 5px;
    color: var(--gold);
    text-transform: uppercase;
    margin-bottom: 20px;
    opacity: 0.95;
    font-weight: 500;
}

.hero-title {
    font-family: var(--font-display);
    font-size: clamp(2.4rem, 7vw, 4.8rem);
    font-weight: 800;
    line-height: 1.02;
    background: linear-gradient(125deg, var(--coral) 0%, var(--gold) 50%, var(--purple) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: 2px;
    margin-bottom: 24px;
    text-shadow: 0 0 60px var(--glow-coral);
}

.hero-subtitle {
    font-size: clamp(1.15rem, 2.5vw, 1.45rem);
    color: var(--text);
    max-width: 680px;
    margin-bottom: 28px;
    line-height: 1.85;
    opacity: 0.85;
}

.hero-hint {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    color: var(--text-secondary);
    border: 1px solid var(--border);
    padding: 8px 16px;
    border-radius: 999px;
    margin-bottom: 48px;
    background: rgba(26, 27, 36, 0.6);
    backdrop-filter: blur(8px);
}

.hero-hint svg { width: 16px; height: 16px; color: var(--coral); }

.section-label {
    font-family: var(--font-display);
    font-size: 0.92rem;
    font-weight: 500;
    letter-spacing: 2.5px;
    color: var(--text);
    text-transform: uppercase;
    margin-bottom: 28px;
    opacity: 0.8;
}

.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 22px;
    max-width: 1160px;
    width: 100%;
}

.topic-card {
    background: var(--glass);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 28px;
    cursor: pointer;
    transition: transform 0.3s cubic-bezier(0.22, 1, 0.36, 1), border-color 0.3s, box-shadow 0.3s;
    text-align: left;
    position: relative;
    overflow: hidden;
}

/* Warm gradient border effect */
.topic-card::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: var(--radius-lg);
    padding: 1px;
    background: linear-gradient(
        135deg,
        rgba(232, 121, 121, 0.3),
        rgba(212, 165, 116, 0.3),
        rgba(139, 107, 174, 0.3)
    );
    -webkit-mask:
        linear-gradient(#fff 0 0) content-box,
        linear-gradient(#fff 0 0);
    mask:
        linear-gradient(#fff 0 0) content-box,
        linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
    opacity: 0;
    transition: opacity 0.3s;
    pointer-events: none;
}

.topic-card::after {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(400px 200px at var(--mx, 50%) var(--my, 0%), rgba(232, 121, 121, 0.08), transparent 70%);
    opacity: 0;
    transition: opacity 0.3s;
    pointer-events: none;
}

.topic-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3), 0 0 30px var(--glow-coral);
}

.topic-card:hover::before { opacity: 1; }
.topic-card:hover::after { opacity: 1; }

.topic-card-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 18px;
}

.topic-icon {
    width: 58px;
    height: 58px;
    display: grid;
    place-items: center;
    font-size: 1.7rem;
    border-radius: 16px;
    background: linear-gradient(135deg, var(--coral-soft), var(--purple-soft));
    border: 1px solid var(--border);
    color: var(--gold);
}

.badge {
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.5px;
    padding: 5px 10px;
    border-radius: 999px;
    background: var(--coral-soft);
    border: 1px solid rgba(232, 121, 121, 0.3);
    color: var(--coral);
    white-space: nowrap;
}

.topic-status {
    width: 26px;
    height: 26px;
    border-radius: 50%;
    display: grid;
    place-items: center;
    border: 2px solid var(--border);
    color: var(--text-dim);
    flex-shrink: 0;
}

.topic-status.done {
    border-color: var(--success);
    background: rgba(124, 185, 139, 0.18);
    color: var(--success);
}

.topic-status svg { width: 15px; height: 15px; }

.topic-number {
    font-family: var(--font-mono);
    font-size: 0.74rem;
    color: var(--gold);
    letter-spacing: 2.5px;
    margin-bottom: 10px;
    opacity: 0.9;
}

.topic-title {
    font-family: var(--font-display);
    font-size: 1.22rem;
    font-weight: 600;
    margin-bottom: 12px;
    line-height: 1.4;
    color: var(--text);
    letter-spacing: 0.3px;
}

.topic-desc {
    font-size: clamp(0.95rem, 2vw, 1.02rem);
    color: var(--text-secondary);
    line-height: 1.75;
    opacity: 0.92;
}

/* ============================================================
   Topic page
   ============================================================ */
.topic-page {
    padding: 28px clamp(16px, 3vw, 32px) 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.back-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--text);
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border);
    font-size: 0.94rem;
    font-weight: 500;
    font-family: inherit;
    padding: 10px 18px;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
    margin-bottom: 28px;
    cursor: pointer;
}

.back-btn:hover {
    color: var(--coral);
    border-color: var(--coral);
    background: var(--coral-soft);
}

.back-btn svg { width: 18px; height: 18px; }

.topic-header { text-align: center; margin-bottom: 36px; }

.topic-header-number {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--gold);
    letter-spacing: 3px;
    margin-bottom: 12px;
}

.topic-header-title {
    font-family: var(--font-display);
    font-size: clamp(1.8rem, 4.5vw, 2.8rem);
    font-weight: 700;
    background: linear-gradient(125deg, var(--coral), var(--gold), var(--purple));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 18px;
    line-height: 1.15;
}

.topic-header-desc {
    color: var(--text-secondary);
    max-width: 800px;
    margin: 0 auto;
    font-size: clamp(1rem, 2.5vw, 1.15rem);
    line-height: 1.8;
    opacity: 1;
}

/* How-to-play strip — warm indie style */
.howto-strip {
    background: linear-gradient(135deg, rgba(139, 107, 174, 0.12), rgba(212, 165, 116, 0.08));
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 20px 24px;
    margin-bottom: 22px;
}

.howto-title {
    font-family: var(--font-display);
    font-size: 0.85rem;
    font-weight: 700;
    letter-spacing: 2px;
    color: var(--gold);
    margin-bottom: 14px;
    text-transform: uppercase;
}

html[lang="th"] .howto-title { font-family: var(--font-thai); letter-spacing: 0.5px; font-size: 1.05rem; }

.howto-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
    gap: 14px;
}

.howto-step {
    display: flex;
    flex-direction: column;
    gap: 8px;
    background: rgba(26, 27, 36, 0.5);
    border-radius: var(--radius-md);
    padding: 14px 16px;
}

.howto-step-header {
    display: flex;
    align-items: center;
    gap: 10px;
}

.howto-step-title {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text);
}

.howto-step-desc {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin: 0;
    padding-left: 40px;
}

.howto-num {
    width: 30px;
    height: 30px;
    flex-shrink: 0;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--coral), var(--gold));
    color: var(--bg-deep);
    font-weight: 800;
    font-size: 1rem;
    display: grid;
    place-items: center;
}

.howto-text {
    font-size: 1.05rem;
    font-weight: 500;
    color: var(--text);
    line-height: 1.55;
    padding-top: 2px;
}

/* Simulation container */
.simulation-container {
    background: var(--glass);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: clamp(18px, 2.5vw, 30px);
    margin-bottom: 26px;
    position: relative;
    overflow: hidden;
}

.challenge-strip {
    display: flex;
    align-items: flex-start;
    gap: 14px;
    padding: 16px 20px;
    margin-bottom: 22px;
    border-radius: var(--radius-md);
    background: linear-gradient(135deg, rgba(232, 121, 121, 0.12), rgba(139, 107, 174, 0.08));
    border: 1px solid rgba(232, 121, 121, 0.28);
    font-size: 0.98rem;
    color: var(--text);
    line-height: 1.6;
}

.challenge-strip .chip {
    font-family: var(--font-display);
    font-size: 0.68rem;
    letter-spacing: 1px;
    color: var(--coral);
    border: 1px solid rgba(232, 121, 121, 0.4);
    padding: 4px 9px;
    border-radius: 6px;
    flex-shrink: 0;
    margin-top: 1px;
}

.sim-canvas-wrap {
    width: 100%;
    height: clamp(300px, 44vw, 440px);
    background: var(--bg-deep);
    border-radius: var(--radius-md);
    position: relative;
    overflow: hidden;
    border: 1px solid var(--border);
}

.sim-canvas-wrap canvas {
    width: 100%;
    height: 100%;
    display: block;
    touch-action: none;
}

.sim-hint {
    position: absolute;
    bottom: 12px;
    left: 12px;
    font-size: 0.92rem;
    color: var(--text);
    background: rgba(11, 13, 20, 0.8);
    padding: 5px 10px;
    border-radius: 6px;
    pointer-events: none;
    backdrop-filter: blur(4px);
}

/* Controls */
.controls-panel {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 24px;
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--border);
}

.control-group { min-width: 0; }

.control-label {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
    font-size: 0.94rem;
    font-weight: 500;
    color: var(--text);
}

.control-value {
    font-family: var(--font-mono);
    color: var(--gold);
    font-size: 0.88rem;
    font-weight: 500;
    background: var(--gold-soft);
    padding: 3px 10px;
    border-radius: 6px;
    border: 1px solid rgba(212, 165, 116, 0.2);
}

.slider {
    width: 100%;
    height: 6px;
    -webkit-appearance: none;
    appearance: none;
    background: linear-gradient(90deg, rgba(232, 121, 121, 0.5), rgba(139, 107, 174, 0.3));
    border-radius: 3px;
    outline: none;
    cursor: pointer;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px; height: 20px;
    background: radial-gradient(circle at 35% 30%, #ffffff, var(--coral));
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 0 14px var(--glow-coral);
    transition: transform 0.15s ease;
}
.slider::-webkit-slider-thumb:hover { transform: scale(1.2); }
.slider::-moz-range-thumb {
    width: 20px; height: 20px;
    background: radial-gradient(circle at 35% 30%, #fff, var(--coral));
    border-radius: 50%;
    cursor: pointer;
    border: none;
    box-shadow: 0 0 14px var(--glow-coral);
}

/* Buttons */
.btn {
    padding: 14px 28px;
    border: none;
    border-radius: var(--radius-sm);
    font-family: var(--font-body);
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    cursor: pointer;
    transition: transform 0.15s ease, box-shadow 0.2s ease, background 0.2s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    white-space: nowrap;
    color: #fff;
}

html[lang="th"] .btn { font-family: var(--font-thai); font-weight: 600; }

.btn svg { width: 20px; height: 20px; }

.btn-primary {
    background: linear-gradient(135deg, var(--coral), var(--gold));
    color: #fff;
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
    box-shadow: 0 6px 22px var(--glow-coral);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 10px 30px var(--glow-coral); }
.btn-primary:active { transform: translateY(0); }

.btn-violet {
    background: linear-gradient(135deg, var(--purple), var(--coral));
    color: #fff;
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
    box-shadow: 0 6px 22px var(--glow-purple);
}
.btn-violet:hover { transform: translateY(-2px); box-shadow: 0 10px 30px var(--glow-purple); }

.btn-secondary {
    background: rgba(255, 255, 255, 0.04);
    color: var(--text);
    border: 1px solid var(--border);
}
.btn-secondary:hover { border-color: var(--coral); background: var(--coral-soft); }

.btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; box-shadow: none; }

.btn.pressed { background: linear-gradient(135deg, var(--success), var(--gold)); }

.btn-group {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    margin-top: 22px;
}

/* Stats */
.stats-panel {
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
    margin-top: 22px;
}

.stat-item {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border);
    padding: 14px 22px;
    border-radius: var(--radius-md);
    text-align: center;
    min-width: 110px;
    flex: 1;
}

.stat-value {
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 700;
    color: var(--gold);
    line-height: 1.1;
}

.stat-label {
    font-size: 0.86rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-top: 6px;
}

/* Quiz */
.quiz-section {
    background: var(--glass);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: clamp(20px, 3vw, 32px);
    margin-bottom: 28px;
}

.quiz-tag {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.74rem;
    font-weight: 500;
    letter-spacing: 2.5px;
    color: var(--purple);
    text-transform: uppercase;
    margin-bottom: 14px;
}

.quiz-question {
    font-size: 1.24rem;
    font-weight: 600;
    margin-bottom: 24px;
    line-height: 1.55;
    color: var(--text);
}

.quiz-options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 12px;
    margin-bottom: 8px;
}

.quiz-option {
    padding: 18px 22px;
    background: rgba(255, 255, 255, 0.03);
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1.02rem;
    font-weight: 500;
    font-family: inherit;
    text-align: left;
    color: var(--text);
    line-height: 1.5;
}

html[lang="th"] .quiz-option { font-family: var(--font-thai); font-weight: 400; }

.quiz-option:hover:not(:disabled) {
    border-color: var(--coral);
    background: var(--coral-soft);
    transform: translateY(-1px);
}

.quiz-option:disabled { cursor: default; }
.quiz-option.correct { border-color: var(--success); background: rgba(124, 185, 139, 0.18); }
.quiz-option.incorrect { border-color: var(--error); background: rgba(232, 121, 121, 0.16); }

.quiz-feedback {
    padding: 20px 22px;
    border-radius: var(--radius-md);
    margin-top: 18px;
    animation: slideIn 0.3s ease;
    font-size: 1rem;
    line-height: 1.65;
    color: var(--text);
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(-8px); }
    to { opacity: 1; transform: translateY(0); }
}

.quiz-feedback.correct { background: rgba(124, 185, 139, 0.15); border: 1px solid var(--success); padding: 16px 20px; border-radius: var(--radius-md); }
.quiz-feedback.incorrect { background: rgba(232, 121, 121, 0.12); border: 1px solid var(--error); padding: 16px 20px; border-radius: var(--radius-md); }
.quiz-feedback strong { display: block; margin-bottom: 8px; font-size: 1.05rem; }
.quiz-feedback.correct strong { color: var(--success); }
.quiz-feedback.incorrect strong { color: var(--error); }
.quiz-feedback .body { color: var(--text); font-size: 0.98rem; }

/* Footer */
footer {
    background: linear-gradient(180deg, transparent, rgba(11, 13, 20, 0.8));
    padding: 52px 24px 60px;
    text-align: center;
    border-top: 1px solid var(--border);
    margin-top: 20px;
}

.credits { max-width: 640px; margin: 0 auto; }

.credits-logo {
    width: 60px;
    height: 60px;
    margin: 0 auto 18px;
    display: block;
    opacity: 0.95;
    filter: drop-shadow(0 0 12px var(--glow-gold));
}

.credits-title {
    font-family: var(--font-display);
    font-size: 1.1rem;
    font-weight: 700;
    letter-spacing: 3px;
    color: var(--gold);
    margin-bottom: 20px;
}

.credits-list {
    list-style: none;
    color: var(--text);
    font-size: 1rem;
    line-height: 2.2;
}

.credits-list .role { color: var(--text-secondary); font-weight: 400; }
.credits-list .name { color: var(--text); font-weight: 600; }

.credits-note {
    margin-top: 24px;
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Confetti */
.confetti { position: fixed; inset: 0; pointer-events: none; z-index: 9999; overflow: hidden; }
.confetti-piece {
    position: absolute;
    width: 9px; height: 9px;
    border-radius: 2px;
    animation: confettiFall 1.3s cubic-bezier(0.2, 0.6, 0.3, 1) forwards;
}
@keyframes confettiFall {
    0% { transform: translateY(0) rotate(0deg); opacity: 1; }
    100% { transform: translateY(420px) rotate(680deg); opacity: 0; }
}

/* Toast */
.toast {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    background: var(--glass);
    backdrop-filter: blur(16px);
    border: 1px solid var(--border);
    color: var(--text);
    padding: 12px 20px;
    border-radius: 999px;
    font-size: 0.9rem;
    z-index: 3000;
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* Responsive — Tablet and Mobile Optimizations */
@media (max-width: 1024px) {
    body { font-size: 17px; }
    .hero-title { font-size: clamp(2rem, 8vw, 3.5rem); }
    .hero-subtitle { font-size: 1.1rem; }
    .topic-title { font-size: 1.15rem; }
    .topic-desc { font-size: 0.98rem; }
    .topic-page { padding: 24px 20px 20px; }
    .simulation-container { padding: clamp(16px, 3vw, 24px); }
    .quiz-question { font-size: 1.15rem; }
    .controls-panel { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
    body {
        font-size: 17px;
        line-height: 1.65;
    }

    /* Better text contrast on mobile */
    .topic-desc,
    .topic-header-desc,
    .quiz-feedback-text,
    .sim-hint {
        color: var(--text-secondary);
        opacity: 1;
    }

    /* Increase touch targets */
    .btn {
        padding: 16px 24px;
        font-size: 1.05rem;
        min-height: 52px;
    }

    .quiz-option {
        padding: 18px 20px;
        font-size: 1rem;
        min-height: 56px;
    }

    /* Better spacing for topic cards */
    .topic-card { padding: 22px; }
    .topic-title { font-size: 1.1rem; margin-bottom: 10px; }
    .topic-desc { font-size: 0.95rem; line-height: 1.65; }
    .topic-icon { width: 50px; height: 50px; font-size: 1.5rem; }

    /* Topic page improvements */
    .topic-page { padding: 20px 16px 20px; }
    .back-btn { padding: 12px 16px; font-size: 0.95rem; }

    /* Controls panel - stack on mobile */
    .controls-panel {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .control-group { padding: 16px; background: rgba(255,255,255,0.02); border-radius: 12px; }
    .control-label { font-size: 1rem; }

    /* Simulation canvas - better height for mobile */
    .sim-canvas-wrap {
        height: clamp(280px, 50vw, 360px);
    }

    /* Quiz section */
    .quiz-section { padding: 20px 18px; }
    .quiz-question { font-size: 1.12rem; margin-bottom: 20px; }
    .quiz-options { grid-template-columns: 1fr; gap: 10px; }

    /* Stats panel */
    .stat-item { min-width: calc(50% - 8px); padding: 16px 14px; }
    .stat-value { font-size: 1.8rem; }
    .stat-label { font-size: 0.85rem; }

    /* Home page */
    .home-hero { padding: 48px 20px 60px; }
    .hero-subtitle { font-size: 1.05rem; padding: 0 10px; }
    .topic-grid { gap: 16px; }

    /* Header */
    .header-center { font-size: 0.85rem; }
    .logo-icon { font-size: 1.3rem; }

    /* Challenge strip */
    .challenge-strip {
        padding: 14px 16px;
        font-size: 0.95rem;
        flex-direction: column;
        gap: 10px;
    }
}

@media (max-width: 480px) {
    body { font-size: 16px; }

    /* Header: drop the wordmark so the 44px sound/lang touch targets never clip.
       The gold SCIUS logo mark stays as branding. */
    .logo-text { display: none; }
    header { gap: 10px; }

    .hero-title { font-size: clamp(1.8rem, 9vw, 2.4rem); }
    .hero-subtitle { font-size: 1rem; }
    .eyebrow { font-size: 0.78rem; letter-spacing: 3px; }

    .topic-card { padding: 18px; }
    .topic-title { font-size: 1.05rem; }
    .topic-desc { font-size: 0.92rem; }

    .topic-page { padding: 16px 14px 16px; }

    .simulation-container { padding: 16px; margin-bottom: 20px; }
    .sim-canvas-wrap { height: clamp(240px, 45vw, 300px); }

    .btn {
        padding: 14px 20px;
        font-size: 1rem;
        width: 100%;
    }

    .quiz-section { padding: 18px 14px; }
    .quiz-question { font-size: 1.05rem; }
    .quiz-option { padding: 16px 18px; font-size: 0.98rem; }

    .stats-panel { gap: 10px; }
    .stat-item { min-width: 100%; }

    .back-btn {
        padding: 10px 14px;
        font-size: 0.9rem;
        margin-bottom: 20px;
    }

    .control-label { font-size: 0.95rem; }
    .control-value { font-size: 0.85rem; }
}

@media (max-width: 360px) {
    body { font-size: 15px; }
    .topic-card { padding: 16px; }
    .btn { padding: 12px 18px; font-size: 0.95rem; }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.001ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.001ms !important;
        scroll-behavior: auto !important;
    }
}

button:focus-visible, a:focus-visible, .quiz-option:focus-visible, .slider:focus-visible {
    outline: 2px solid var(--coral);
    outline-offset: 2px;
}

::selection { background: var(--coral); color: #ffffff; }

::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--bg-deep); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 5px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-dim); }