/* ===== Reset & Base ===== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg: #141414;
    --bg-card: #1c1c1c;
    --bg-card-hover: #232323;
    --surface: rgba(255, 255, 255, 0.04);
    --border: rgba(255, 255, 255, 0.1);
    --text: #e8e6e3;
    --text-muted: #888580;
    --accent: #e2a247;
    --accent-hover: #f0b55e;
    --accent-glow: rgba(226, 162, 71, 0.12);
    --accent-dim: rgba(226, 162, 71, 0.06);
    --green: #5cb85c;
    --green-bg: rgba(92, 184, 92, 0.08);
    --red: #d9534f;
    --red-bg: rgba(217, 83, 79, 0.08);
    --yellow: #e2a247;
    --radius: 8px;
    --radius-sm: 6px;
    --ease: cubic-bezier(0.23, 1, 0.32, 1);
    --transition: 0.3s cubic-bezier(0.23, 1, 0.32, 1);
    --font: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --font-mono: 'JetBrains Mono', 'SF Mono', 'Cascadia Code', 'Consolas', monospace;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    overflow-x: hidden;
    transition: background-color var(--transition), color var(--transition);
    position: relative;
}

/* Clean background — no ambient gradient glow */

/* Noise overlay for texture */
body::after {
    content: '';
    position: fixed;
    inset: 0;
    z-index: -1;
    opacity: 0.035;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
    background-repeat: repeat;
    background-size: 256px 256px;
    pointer-events: none;
}

body.light-theme {
    --bg: #fafaf8;
    --bg-card: #ffffff;
    --bg-card-hover: #f5f5f3;
    --surface: rgba(0, 0, 0, 0.03);
    --border: rgba(0, 0, 0, 0.1);
    --text: #1a1a18;
    --text-muted: #6b6966;
    --accent: #c4882e;
    --accent-hover: #a87425;
    --accent-glow: rgba(196, 136, 46, 0.1);
    --accent-dim: rgba(196, 136, 46, 0.05);
}

.theme-toggle-btn {
    background: var(--surface);
    border: 1px solid var(--border);
    color: var(--text);
    font-size: 1.1rem;
    cursor: pointer;
    vertical-align: middle;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    transition: all var(--transition);
}
.theme-toggle-btn:hover {
    transform: scale(1.1);
    background: var(--accent-dim);
    border-color: var(--accent);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    color: var(--accent-hover);
}

/* ===== Navigation ===== */
#navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(10, 14, 23, 0.7);
    backdrop-filter: blur(20px) saturate(160%);
    -webkit-backdrop-filter: blur(20px) saturate(160%);
    border-bottom: 1px solid var(--border);
    padding: 0 24px;
    transition: background var(--transition), box-shadow var(--transition);
}

body.light-theme #navbar {
    background: rgba(248, 250, 252, 0.75);
}

#navbar.scrolled {
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.15);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 8px;
    letter-spacing: -0.02em;
}

.nav-logo:hover {
    color: var(--accent);
}

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

.nav-links {
    list-style: none;
    display: flex;
    gap: 32px;
}

.nav-links a {
    color: var(--text-muted);
    font-size: 0.9rem;
    font-weight: 500;
    transition: color var(--transition);
    letter-spacing: 0.01em;
}

.nav-links a:hover {
    color: var(--text);
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text);
    font-size: 1.5rem;
    cursor: pointer;
}

/* ===== Hero ===== */
#hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 120px 24px 80px;
    max-width: 1200px;
    margin: 0 auto;
    gap: 80px;
}

.hero-content {
    flex: 1;
}

.hero-kicker {
    display: inline-block;
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--accent);
    margin-bottom: 16px;
    padding: 6px 16px;
    border: 1px solid rgba(226, 162, 71, 0.25);
    border-radius: 100px;
    background: var(--accent-dim);
}

.hero-content h1 {
    font-size: clamp(2.8rem, 5vw, 4.2rem);
    font-weight: 800;
    line-height: 1.12;
    margin-bottom: 28px;
    color: var(--text);
    letter-spacing: -0.04em;
    text-wrap: balance;
}

.hero-content h1 .gradient-text {
    background: linear-gradient(135deg, var(--accent) 0%, #f0b55e 40%, var(--green) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.15rem;
    color: var(--text-muted);
    max-width: 520px;
    margin-bottom: 40px;
    line-height: 1.8;
    text-wrap: pretty;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    margin-bottom: 48px;
}

.hero-stats {
    display: flex;
    gap: 36px;
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 16px 20px;
    border-radius: var(--radius);
    transition: all var(--transition);
    border: 1px solid transparent;
}

.stat:hover {
    border-color: var(--border);
    background: var(--surface);
}

.stat:hover .stat-num {
    color: var(--accent-hover);
}

.stat-num {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--accent);
    line-height: 1.2;
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-top: 4px;
}

.hero-visual {
    flex: 0 0 420px;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

/* Glow behind 3D model */
.hero-visual::before {
    content: '';
    position: absolute;
    width: 340px;
    height: 340px;
    border-radius: 50%;
    background: radial-gradient(circle, var(--accent-glow) 0%, rgba(226, 162, 71, 0.04) 60%, transparent 80%);
    filter: blur(40px);
    z-index: -1;
    animation: heroGlow 6s ease-in-out infinite alternate;
}

@keyframes heroGlow {
    0%   { opacity: 0.6; transform: scale(1); }
    100% { opacity: 1; transform: scale(1.08); }
}

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: 13px 30px;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    border: none;
    font-family: var(--font);
    letter-spacing: 0.01em;
}

.btn-primary {
    background: var(--accent);
    color: #141414;
    font-weight: 700;
}

.btn-primary:hover {
    background: var(--accent-hover);
    color: #141414;
}

.btn-outline {
    background: transparent;
    color: var(--text-muted);
    border: 1.5px solid var(--border);
}

.btn-outline:hover {
    border-color: var(--text);
    color: var(--text);
}

.btn-small {
    padding: 8px 20px;
    font-size: 0.88rem;
}

.btn-outline.btn-small {
    background: var(--surface);
    color: var(--accent);
    border: 1.5px solid rgba(226, 162, 71, 0.3);
}

.btn-outline.btn-small:hover {
    background: var(--accent-dim);
    border-color: var(--accent);
}

/* ===== Progress Bar ===== */
#progress-bar {
    padding: 36px 0;
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
}

.progress-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.progress-header h3 {
    font-size: 1rem;
    font-weight: 600;
}

#progress-text {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.progress-track {
    width: 100%;
    height: 8px;
    background: var(--surface);
    border-radius: 100px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent), var(--green));
    border-radius: 100px;
    transition: width 0.5s ease;
}

/* ===== Section Titles ===== */
.section-title {
    font-size: clamp(1.8rem, 3vw, 2.25rem);
    font-weight: 800;
    margin-bottom: 12px;
    text-align: center;
    letter-spacing: -0.03em;
    text-wrap: balance;
}

.section-subtitle {
    color: var(--text-muted);
    text-align: center;
    max-width: 600px;
    margin: 0 auto 60px;
    text-wrap: pretty;
}

/* ===== Modules ===== */
#modules {
    padding: 100px 0 120px;
}

/* Phase Headers */
.phase-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-top: 64px;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
}

.phase-header:first-of-type {
    margin-top: 0;
}

.phase-number {
    font-size: 0.72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--accent);
    background: var(--accent-dim);
    border: 1px solid rgba(226, 162, 71, 0.2);
    padding: 4px 12px;
    border-radius: 100px;
    white-space: nowrap;
}

.phase-title {
    font-size: 1.3rem;
    font-weight: 700;
    letter-spacing: -0.01em;
    color: var(--text);
}

.phase-desc {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-left: auto;
}

@media (max-width: 768px) {
    .phase-header {
        flex-wrap: wrap;
        gap: 8px;
    }
    .phase-desc {
        margin-left: 0;
        width: 100%;
    }
}

.modules-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 20px;
    margin-bottom: 16px;
}

.module-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    transition: all var(--transition);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    position: relative;
    overflow: hidden;
}

/* Clean top accent line on cards */
.module-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--accent);
    opacity: 0;
    transition: opacity var(--transition);
}

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

.module-card:hover {
    border-color: rgba(226, 162, 71, 0.2);
    background: var(--bg-card-hover);
    transform: translateY(-4px);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(226, 162, 71, 0.06);
}

.module-card.completed {
    border-color: rgba(92, 184, 92, 0.3);
}

.module-card.completed::before {
    opacity: 1;
    background: var(--green);
}

.module-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 12px;
}

.module-number {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-muted);
    opacity: 0.25;
    letter-spacing: -0.02em;
}

.module-tag {
    background: var(--surface);
    color: var(--text-muted);
    padding: 4px 12px;
    border-radius: 100px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    border: 1px solid rgba(226, 162, 71, 0.15);
}

.module-card h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 8px;
    letter-spacing: -0.01em;
}

.module-desc {
    color: var(--text-muted);
    margin-bottom: 20px;
    font-size: 0.92rem;
    line-height: 1.6;
}

/* Card entrance stagger — driven by scroll-reveal (.reveal / .active) in shared.js.
   We only set the transition-delay here; opacity & transform live on .reveal / .reveal.active. */
.module-card-link:nth-child(1) .module-card { transition-delay: 0.05s; }
.module-card-link:nth-child(2) .module-card { transition-delay: 0.10s; }
.module-card-link:nth-child(3) .module-card { transition-delay: 0.12s; }
.module-card-link:nth-child(4) .module-card { transition-delay: 0.14s; }
.module-card-link:nth-child(5) .module-card { transition-delay: 0.16s; }
.module-card-link:nth-child(6) .module-card { transition-delay: 0.18s; }
.module-card-link:nth-child(7) .module-card { transition-delay: 0.20s; }
.module-card-link:nth-child(8) .module-card { transition-delay: 0.22s; }
.module-card-link:nth-child(9) .module-card { transition-delay: 0.24s; }
.module-card-link:nth-child(10) .module-card { transition-delay: 0.26s; }
.module-card-link:nth-child(11) .module-card { transition-delay: 0.28s; }
.module-card-link:nth-child(12) .module-card { transition-delay: 0.30s; }
.module-card-link:nth-child(13) .module-card { transition-delay: 0.32s; }
.module-card-link:nth-child(14) .module-card { transition-delay: 0.34s; }
.module-card-link:nth-child(15) .module-card { transition-delay: 0.36s; }

/* Concept Blocks */
.concept-block {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    margin: 24px 0;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.concept-block h5 {
    font-size: 1.1rem;
    margin-bottom: 16px;
    color: var(--text);
}

/* Comparison Grid */
.comparison-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 16px;
}

.compare-item {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 20px;
    border: 1px solid var(--border);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: border-color var(--transition), transform var(--transition);
}

.compare-item h6 {
    font-size: 1rem;
    margin-bottom: 8px;
    color: var(--accent);
}

.compare-item ul {
    list-style: none;
    padding: 0;
}

.compare-item ul li {
    padding: 4px 0;
    padding-left: 16px;
    position: relative;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.compare-item ul li::before {
    content: '›';
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: bold;
}

.compare-item p {
    font-size: 0.9rem;
}

/* Workflow Steps */
.workflow-steps {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.workflow-step {
    display: flex;
    gap: 16px;
    align-items: flex-start;
}

.step-num {
    flex: 0 0 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--accent), var(--accent));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1rem;
    box-shadow: 0 2px 10px var(--accent-glow);
}

.workflow-step p {
    font-size: 0.9rem;
    margin-top: 4px;
}

/* Feature Grid */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    text-align: center;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.feature-icon {
    font-size: 2rem;
    margin-bottom: 8px;
    color: var(--accent);
}

.feature-card strong {
    display: block;
    margin-bottom: 8px;
}

.feature-card p {
    font-size: 0.85rem;
}

/* Feature List */
.feature-list {
    list-style: none;
    padding: 0;
}

.feature-list li {
    padding: 8px 0 8px 20px;
    position: relative;
    color: var(--text-muted);
}

.feature-list li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--accent);
}

/* Tip Box */
.tip-box {
    background: var(--accent-dim);
    border-left: 4px solid var(--accent);
    border-radius: 0 var(--radius) var(--radius) 0;
    padding: 20px 24px;
    margin: 24px 0;
    color: var(--text-muted);
    border: 1px solid rgba(226, 162, 71, 0.1);
    border-left: 4px solid var(--accent);
}

.tip-box strong {
    color: var(--accent);
}

/* Table */
.info-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 12px;
}

.info-table th,
.info-table td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
    font-size: 0.9rem;
}

.info-table th {
    color: var(--accent);
    font-weight: 600;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.info-table td {
    color: var(--text-muted);
}

/* Tolerance Visuals */
.tolerance-visual {
    height: 40px;
    margin-top: 12px;
    border-radius: 4px;
    position: relative;
    overflow: hidden;
}

.tolerance-visual.clearance {
    background: repeating-linear-gradient(
        90deg,
        var(--accent) 0px, var(--accent) 40px,
        transparent 40px, transparent 50px,
        var(--green) 50px, var(--green) 90px,
        transparent 90px, transparent 100px
    );
    opacity: 0.3;
}

.tolerance-visual.transition {
    background: repeating-linear-gradient(
        90deg,
        var(--accent) 0px, var(--accent) 45px,
        transparent 45px, transparent 47px,
        var(--green) 47px, var(--green) 92px,
        transparent 92px, transparent 94px
    );
    opacity: 0.3;
}

.tolerance-visual.interference {
    background: repeating-linear-gradient(
        90deg,
        var(--accent) 0px, var(--accent) 48px,
        var(--yellow) 48px, var(--yellow) 52px,
        var(--green) 52px, var(--green) 100px
    );
    opacity: 0.3;
}

/* DOF Visual */
.dof-visual {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-top: 16px;
}

.dof-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px;
    text-align: center;
}

.dof-icon {
    font-size: 2rem;
    display: block;
    margin-bottom: 4px;
}

.dof-icon.translate { color: var(--accent); }
.dof-icon.rotate { color: var(--green); }

.dof-item span {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Joint List */
.joint-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.joint-item {
    display: flex;
    gap: 16px;
    align-items: flex-start;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    transition: border-color var(--transition), transform var(--transition);
}

.joint-item:hover {
    border-color: rgba(226, 162, 71, 0.2);
    transform: translateY(-2px);
}

.joint-icon {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    flex-shrink: 0;
}

.joint-icon.revolute {
    background: conic-gradient(var(--accent), transparent 270deg, var(--accent));
    border: 3px solid var(--accent);
}

.joint-icon.prismatic {
    background: linear-gradient(180deg, var(--accent) 30%, transparent 30%, transparent 70%, var(--accent) 70%);
    border: 3px solid var(--accent);
    border-radius: 8px;
}

.joint-icon.cylindrical {
    background: conic-gradient(var(--green), transparent 180deg, var(--green));
    border: 3px solid var(--green);
}

.joint-icon.rigid {
    background: var(--surface);
    border: 3px solid var(--text-muted);
}

.joint-item strong {
    color: var(--text);
}

.joint-item p {
    font-size: 0.9rem;
    margin-top: 4px;
}

/* Mechanism List */
.mechanism-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.mechanism-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    transition: border-color var(--transition);
}

.mechanism-item:hover {
    border-color: rgba(226, 162, 71, 0.2);
}

.mechanism-item h6 {
    color: var(--accent);
    margin-bottom: 6px;
}

.mechanism-item p {
    font-size: 0.9rem;
}

/* Formula Box */
.formula-box {
    background: var(--bg-card);
    border: 1px solid var(--accent);
    border-radius: var(--radius-sm);
    padding: 20px;
    margin: 16px 0;
    text-align: center;
}

.formula-box p {
    margin-bottom: 6px;
}

.formula-example {
    font-size: 1.1rem;
    color: var(--text);
}

.formula-note {
    color: var(--green);
    font-weight: 600;
    font-size: 0.9rem;
}

/* Code Example */
.code-example {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 20px;
    margin-top: 12px;
}

.code-example code {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    color: var(--green);
    line-height: 1.8;
}

/* Folder Tree */
.folder-tree {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 20px;
    margin-top: 12px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 2;
}

.folder { padding-left: 20px; color: var(--accent); }
.file { padding-left: 20px; color: var(--text-muted); }
.folder-tree > .folder { padding-left: 0; }

/* Checklist */
.checklist {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.check-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 0;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 0.95rem;
}

.check-item input[type="checkbox"] {
    width: 18px;
    height: 18px;
    accent-color: var(--green);
    cursor: pointer;
}

/* Mistakes Grid */
.mistakes-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
}

.mistake-card {
    padding: 16px;
    border-radius: var(--radius-sm);
}

.mistake-card h6 {
    margin-bottom: 8px;
    font-size: 0.95rem;
}

.mistake-card.bad {
    background: var(--red-bg);
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.mistake-card.bad h6 {
    color: var(--red);
}

.mistake-card.good {
    background: var(--green-bg);
    border: 1px solid rgba(34, 197, 94, 0.2);
}

.mistake-card.good h6 {
    color: var(--green);
}

.mistake-card p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* ===== Interactive Demos ===== */
.interactive-container {
    margin: 28px 0;
}

.interactive-header {
    margin-bottom: 16px;
}

.interactive-header h5 {
    font-size: 1.05rem;
    color: var(--accent);
    margin-bottom: 4px;
}

.interactive-header p {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.interactive-container canvas {
    width: 100%;
    max-width: 500px;
    display: block;
    margin: 0 auto;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    background: rgba(0, 0, 0, 0.2);
}

.extrude-demo,
.gear-demo,
.linkage-demo,
.dof-demo,
.print-demo,
.cam-demo,
.parametric-demo,
.tolerance-demo {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.extrude-controls,
.gear-controls,
.linkage-controls,
.dof-controls,
.print-controls,
.cam-controls,
.parametric-controls,
.tolerance-controls {
    margin-top: 16px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    align-items: center;
    justify-content: center;
}

.demo-btn {
    padding: 8px 18px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--surface);
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    font-family: var(--font);
}

.demo-btn:hover {
    border-color: var(--accent);
    color: var(--text);
    transform: translateY(-1px);
}

.demo-btn.active {
    background: var(--accent-dim);
    border-color: var(--accent);
    color: var(--accent);
    box-shadow: 0 2px 8px var(--accent-glow);
}

.extrude-slider-wrap,
.linkage-controls label,
.print-controls label {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--text-muted);
    font-size: 0.9rem;
    justify-content: center;
    margin-top: 12px;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    height: 6px;
    background: var(--surface);
    border-radius: 100px;
    outline: none;
    cursor: pointer;
    flex: 0 0 200px;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--accent);
    cursor: pointer;
    border: 2px solid var(--bg);
    box-shadow: 0 0 6px var(--accent-glow);
}

.demo-description {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 12px;
    font-style: italic;
}

/* Gear readout */
.gear-readout {
    display: flex;
    gap: 24px;
    justify-content: center;
    margin-top: 16px;
    flex-wrap: wrap;
}

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

.readout-label {
    display: block;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-muted);
    margin-bottom: 4px;
}

.readout-value {
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--text);
}

.gear-control {
    flex: 1;
    min-width: 200px;
}

.gear-control label {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-muted);
    font-size: 0.85rem;
    flex-wrap: wrap;
}

.gear-control input[type="range"] {
    width: 100%;
    flex: 1;
}

/* DOF controls */
.dof-controls {
    display: grid !important;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px !important;
    margin-top: 16px;
}

.dof-toggle {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8rem;
    color: var(--text-muted);
    cursor: pointer;
    padding: 8px 10px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
    background: var(--surface);
    transition: all var(--transition);
}

.dof-toggle:has(input:checked) {
    background: rgba(226, 162, 71, 0.1);
    border-color: var(--accent);
    color: var(--text);
}

.dof-toggle input {
    accent-color: var(--accent);
}

.toggle-indicator {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    margin-left: auto;
}

.tx-color { background: #ef4444; }
.ty-color { background: #22c55e; }
.tz-color { background: #3b82f6; }
.rx-color { background: #f97316; }
.ry-color { background: #a855f7; }
.rz-color { background: #eab308; }

.dof-readout {
    text-align: center;
    margin-top: 16px;
}

.dof-count {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text);
}

.dof-count span {
    color: var(--accent);
    font-size: 2rem;
}

.dof-status {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-top: 4px;
}

/* Linkage info */
.linkage-info {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-top: 12px;
    flex-wrap: wrap;
}

.linkage-info span {
    font-size: 0.8rem;
    color: var(--text-muted);
    padding: 4px 10px;
    background: var(--surface);
    border-radius: 4px;
}

/* Print orientation meters */
.print-meters {
    width: 100%;
    max-width: 400px;
    margin: 12px auto 0;
}

.meter {
    margin-bottom: 8px;
}

.meter-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    display: block;
    margin-bottom: 4px;
}

.meter-bar {
    height: 10px;
    background: var(--surface);
    border-radius: 100px;
    overflow: hidden;
}

.meter-fill {
    height: 100%;
    border-radius: 100px;
    transition: width 0.3s ease, background 0.3s ease;
    width: 100%;
}

.strength-fill {
    background: #22c55e;
}

.meter-value {
    font-size: 0.8rem;
    font-weight: 600;
    margin-top: 4px;
    display: block;
}

/* ===== 3D Model Viewers ===== */
.model-viewer-wrap {
    margin-bottom: 28px;
}

model-viewer {
    --poster-color: transparent;
}

model-viewer::part(default-progress-bar) {
    background: var(--accent);
    height: 3px;
}

.model-caption {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 10px;
    font-style: italic;
}

.model-pair {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.model-single {
    min-width: 0;
}

/* ===== Quiz ===== */
#quiz-section {
    padding: 100px 0;
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.quiz-container {
    max-width: 700px;
    margin: 0 auto;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 40px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.quiz-progress {
    margin-bottom: 28px;
}

#quiz-progress-text {
    font-size: 0.9rem;
    color: var(--text-muted);
    display: block;
    margin-bottom: 8px;
}

.quiz-progress-bar {
    height: 6px;
    background: var(--bg);
    border-radius: 100px;
    overflow: hidden;
}

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

.quiz-question {
    margin-bottom: 24px;
}

.quiz-question h4 {
    font-size: 1.15rem;
    margin-bottom: 20px;
    line-height: 1.5;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.quiz-option {
    display: block;
    padding: 14px 18px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-left: 4px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition);
    font-size: 0.95rem;
    color: var(--text-muted);
    text-align: left;
}

.quiz-option:hover {
    border-color: rgba(226, 162, 71, 0.2);
    border-left-color: var(--accent);
    background: var(--accent-dim);
    color: var(--text);
    transform: translateX(4px);
}

.quiz-option.selected {
    border-color: var(--accent);
    border-left-color: var(--accent);
    background: var(--accent-dim);
    color: var(--text);
    box-shadow: 0 2px 12px var(--accent-glow);
}

.quiz-option.correct {
    border-color: var(--green);
    background: var(--green-bg);
    color: var(--green);
}

.quiz-option.incorrect {
    border-color: var(--red);
    background: var(--red-bg);
    color: var(--red);
}

.quiz-controls {
    display: flex;
    justify-content: space-between;
    margin-top: 24px;
}

.quiz-results {
    text-align: center;
    padding: 24px 0;
}

.score-display {
    margin: 24px 0;
}

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

.score-label {
    font-size: 1.2rem;
    color: var(--text-muted);
}

#quiz-message {
    margin-bottom: 24px;
    font-size: 1.1rem;
}

.quiz-option:disabled {
    cursor: default;
    opacity: 0.9;
}

.quiz-option:disabled:hover {
    border-color: var(--border);
    background: var(--bg-card);
}

.quiz-option.correct:disabled:hover {
    border-color: var(--green);
    background: var(--green-bg);
}

.quiz-option.incorrect:disabled:hover {
    border-color: var(--red);
    background: var(--red-bg);
}

.quiz-module-tag {
    display: inline-block;
    background: rgba(226, 162, 71, 0.12);
    color: var(--accent);
    padding: 3px 10px;
    border-radius: 100px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 12px;
}

.quiz-explanation {
    margin-top: 16px;
    padding: 16px 20px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    line-height: 1.6;
    animation: fadeSlideIn 0.3s ease;
}

.quiz-explanation.correct {
    background: var(--green-bg);
    border-left: 3px solid var(--green);
    color: var(--text-muted);
}

.quiz-explanation.correct strong {
    color: var(--green);
}

.quiz-explanation.incorrect {
    background: var(--red-bg);
    border-left: 3px solid var(--red);
    color: var(--text-muted);
}

.quiz-explanation.incorrect strong {
    color: var(--red);
}

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

/* Quiz Review */
.quiz-review {
    margin-top: 32px;
    text-align: left;
}

.quiz-review h4 {
    font-size: 1.1rem;
    margin-bottom: 20px;
    text-align: center;
    color: var(--text);
}

.review-item {
    padding: 16px 20px;
    border-radius: var(--radius-sm);
    margin-bottom: 12px;
    border-left: 3px solid;
}

.review-item.review-correct {
    background: rgba(34, 197, 94, 0.05);
    border-left-color: var(--green);
}

.review-item.review-incorrect {
    background: rgba(239, 68, 68, 0.05);
    border-left-color: var(--red);
}

.review-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 8px;
}

.review-icon {
    font-weight: 800;
    font-size: 1.1rem;
}

.review-correct .review-icon { color: var(--green); }
.review-incorrect .review-icon { color: var(--red); }

.review-q-num {
    font-weight: 700;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.review-module {
    font-size: 0.75rem;
    color: var(--accent);
    background: rgba(226, 162, 71, 0.1);
    padding: 2px 8px;
    border-radius: 100px;
}

.review-question {
    font-size: 0.95rem;
    color: var(--text);
    margin-bottom: 6px;
    font-weight: 500;
}

.review-answer {
    font-size: 0.85rem;
    margin-bottom: 6px;
}

.correct-text {
    color: var(--green);
    display: block;
}

.incorrect-text {
    color: var(--red);
    display: block;
    text-decoration: line-through;
    opacity: 0.7;
}

.review-explanation {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.5;
}

/* Quiz Dynamic Elements (generated by quiz.js) */
.quiz-question-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    margin-bottom: 24px;
}

.quiz-question-text {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--text);
    line-height: 1.5;
    margin-bottom: 20px;
}

.quiz-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    margin-top: 24px;
}

.quiz-submit {
    display: inline-block;
    padding: 10px 24px;
    background: var(--accent);
    color: #ffffff;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    font-family: var(--font);
    transition: all var(--transition);
}

.quiz-submit:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
}

.quiz-retry {
    display: inline-block;
    padding: 10px 24px;
    background: transparent;
    color: var(--accent);
    border: 1.5px solid var(--accent);
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    font-family: var(--font);
    transition: all var(--transition);
}

.quiz-retry:hover {
    background: rgba(226, 162, 71, 0.1);
}

.quiz-score {
    text-align: center;
    padding: 32px 0;
}

.quiz-score-number {
    font-size: 4rem;
    font-weight: 800;
    color: var(--accent);
    display: block;
    line-height: 1;
}

.quiz-score-label {
    font-size: 1.1rem;
    color: var(--text-muted);
    margin-top: 8px;
    display: block;
}

.quiz-review-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 20px;
    margin-bottom: 12px;
    border-left: 3px solid var(--border);
}

.quiz-review-item.correct {
    border-left-color: var(--green);
}

.quiz-review-item.incorrect {
    border-left-color: var(--red);
}

.quiz-review-question {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 8px;
}

.quiz-review-answer {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 6px;
}

.quiz-review-explanation {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.5;
    padding-top: 8px;
    border-top: 1px solid var(--border);
    margin-top: 8px;
}

/* ===== Glossary ===== */
#glossary {
    padding: 100px 0;
}

.glossary-search {
    max-width: 440px;
    margin: 0 auto 40px;
}

.glossary-search input {
    width: 100%;
    padding: 14px 22px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    font-size: 1rem;
    font-family: var(--font);
    outline: none;
    transition: all var(--transition);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.glossary-search input::placeholder {
    color: var(--text-muted);
}

.glossary-search input:focus {
    border-color: var(--accent);
}

.glossary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 16px;
}

.glossary-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 22px;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: border-color var(--transition), transform var(--transition);
}

.glossary-item:hover {
    border-color: rgba(226, 162, 71, 0.2);
    transform: translateY(-2px);
}

.glossary-item dt {
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 6px;
}

.glossary-item dd {
    color: var(--text-muted);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* ===== Resources ===== */
#resources {
    padding: 100px 0;
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
}

.resource-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: border-color var(--transition), transform var(--transition);
}

.resource-card:hover {
    border-color: rgba(226, 162, 71, 0.2);
    transform: translateY(-3px);
}

.resource-card h4 {
    font-size: 1.1rem;
    margin-bottom: 16px;
    color: var(--text);
}

.resource-card ul {
    list-style: none;
    padding: 0;
}

.resource-card li {
    padding: 6px 0;
    color: var(--text-muted);
    font-size: 0.9rem;
    padding-left: 16px;
    position: relative;
}

.resource-card li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--accent);
}

/* ===== Multi-Page: Module Page Layout ===== */
.module-page {
    padding: 100px 0 60px;
    min-height: 100vh;
}

.module-page-header {
    margin-bottom: 36px;
}

.module-page-header h1 {
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 8px;
}

.module-page-header .module-desc {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin-bottom: 0;
}

.module-page-header .module-header {
    margin-bottom: 12px;
}

.back-link {
    display: inline-block;
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 20px;
    transition: color var(--transition);
}

.back-link:hover {
    color: var(--accent);
}

/* Prev / Next navigation at bottom of module pages */
.module-nav-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 48px;
    padding-top: 32px;
    border-top: 1px solid var(--border);
    gap: 16px;
}

.module-nav-bottom > div {
    flex: 1;
}

.module-nav-bottom > div:last-child {
    text-align: right;
}

/* Module card links on index page */
.module-card-link {
    text-decoration: none;
    color: inherit;
    display: block;
}

.module-card-link:hover {
    color: inherit;
}

.module-card-link .module-card {
    cursor: pointer;
}

.module-card-btn {
    display: inline-block;
    margin-top: 4px;
    transition: all var(--transition);
}

.module-card:hover .module-card-btn {
    border-color: var(--accent);
    color: var(--accent);
}

/* Completed badge */
.completed-badge {
    margin-left: auto;
    background: var(--green);
    color: white;
    width: 26px;
    height: 26px;
    border-radius: 50%;
    display: flex !important;
    align-items: center;
    justify-content: center;
    font-size: 0.85rem;
    font-weight: 700;
}

.module-card.completed .completed-badge {
    display: flex !important;
}

.module-card:not(.completed) .completed-badge {
    display: none !important;
}

.module-card.completed .module-card-btn {
    background: rgba(34, 197, 94, 0.1);
    border-color: var(--green);
    color: var(--green);
}

/* Active nav link */
.nav-links a.active {
    color: var(--text);
    position: relative;
}

.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--accent);
    border-radius: 100px;
}

/* ===== Content Sections (module pages) ===== */
.content-section {
    margin-top: 32px;
}

.content-section h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text);
}

.content-section h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 12px;
    margin-top: 32px;
}

.content-section p {
    margin-bottom: 16px;
    color: var(--text-muted);
}

/* ===== Feature Cards Grid ===== */
.feature-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 16px;
}

/* ===== Model Card ===== */
.model-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 12px;
    overflow: hidden;
}

/* ===== Footer ===== */
footer {
    padding: 48px 0;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.85rem;
    border-top: 1px solid var(--border);
    letter-spacing: 0.01em;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    #hero {
        flex-direction: column;
        text-align: center;
        padding-top: 120px;
        gap: 40px;
    }

    .hero-subtitle {
        margin: 0 auto 36px;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-stats {
        justify-content: center;
        gap: 12px;
        flex-wrap: wrap;
    }

    .stat {
        padding: 12px 16px;
    }

    .hero-visual {
        flex: none;
    }

    .hero-visual model-viewer {
        width: 280px !important;
        height: 280px !important;
    }

    .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: rgba(10, 14, 23, 0.9);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        padding: 16px 24px;
        gap: 16px;
        border-bottom: 1px solid var(--border);
    }

    body.light-theme .nav-links {
        background: rgba(248, 250, 252, 0.9);
    }

    .nav-links.open {
        display: flex;
    }

    .nav-toggle {
        display: block;
    }

    .modules-grid {
        grid-template-columns: 1fr;
    }

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

    .mistakes-grid {
        grid-template-columns: 1fr;
    }

    .comparison-grid {
        grid-template-columns: 1fr;
    }

    .feature-grid {
        grid-template-columns: 1fr 1fr;
    }

    .dof-controls {
        grid-template-columns: repeat(2, 1fr) !important;
    }

    .gear-readout {
        gap: 16px;
    }

    .interactive-container canvas {
        max-width: 100%;
    }

    .model-pair {
        grid-template-columns: 1fr;
    }

    .module-nav-bottom {
        flex-direction: column;
        gap: 20px;
    }

    .module-nav-bottom > div,
    .module-nav-bottom > div:last-child {
        text-align: center;
    }

    .module-page-header h1 {
        font-size: 1.6rem;
    }

    #modules {
        padding: 80px 0 100px;
    }
}

@media (max-width: 480px) {
    .feature-grid {
        grid-template-columns: 1fr;
    }

    .module-card {
        padding: 22px 18px;
    }

    .quiz-container {
        padding: 24px 18px;
    }

    .hero-stats {
        gap: 8px;
    }

    .stat {
        padding: 10px 12px;
        font-size: 0.9rem;
    }
}

/* ===== Scroll Reveal Animations ===== */
.reveal {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.8s var(--ease), transform 0.8s var(--ease);
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

/* ===== Focus Styles (Accessibility) ===== */
a:focus-visible,
button:focus-visible,
input:focus-visible,
.quiz-option:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

/* ===== Skip-to-content (Accessibility) ===== */
.skip-link {
    position: absolute;
    top: -100%;
    left: 16px;
    background: var(--accent);
    color: #fff;
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    z-index: 9999;
    font-weight: 600;
    font-size: 0.9rem;
}
.skip-link:focus {
    top: 8px;
}

/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
    .reveal { opacity: 1; transform: none; }
}

/* ===== Knowledge Check ===== */
.knowledge-check {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    margin: 48px 0;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.kc-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 24px;
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--accent);
}

.kc-question {
    background: var(--surface);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 16px;
}

.kc-question h4 {
    margin-bottom: 12px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text);
}

.kc-options {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.kc-option {
    display: block;
    width: 100%;
    padding: 12px 16px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text);
    font-size: 0.9rem;
    cursor: pointer;
    text-align: left;
    transition: all 0.2s ease;
    font-family: var(--font);
}

.kc-option:hover:not(:disabled) {
    border-color: var(--accent);
    background: var(--accent-glow);
}

.kc-option:disabled {
    cursor: default;
    opacity: 0.7;
}

.kc-option.kc-correct {
    border-color: var(--green) !important;
    background: var(--green-bg) !important;
    color: var(--green) !important;
    opacity: 1 !important;
    font-weight: 600;
}

.kc-option.kc-incorrect {
    border-color: var(--red) !important;
    background: var(--red-bg) !important;
    color: var(--red) !important;
    opacity: 1 !important;
}

.kc-explanation {
    margin-top: 12px;
    padding: 12px 16px;
    border-radius: 6px;
    font-size: 0.85rem;
    line-height: 1.5;
}

.kc-explain-correct {
    background: var(--green-bg);
    border-left: 3px solid var(--green);
    color: var(--green);
}

.kc-explain-incorrect {
    background: var(--red-bg);
    border-left: 3px solid var(--red);
    color: var(--red);
}

.kc-score {
    text-align: center;
    padding: 24px;
    margin-top: 16px;
    background: var(--surface);
    border-radius: 8px;
}

.kc-score .score-number {
    font-size: 2rem;
    font-weight: 800;
    color: var(--accent);
}

.kc-score p {
    margin-top: 8px;
    color: var(--text-muted);
}

.kc-retry {
    margin-top: 16px;
    padding: 10px 24px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 6px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    font-family: var(--font);
    transition: background 0.2s ease;
}

.kc-retry:hover {
    background: var(--accent-hover);
}

/* ===== Learning Objectives ===== */
.learning-objectives {
    background: linear-gradient(135deg, rgba(6, 150, 215, 0.08), rgba(6, 150, 215, 0.02));
    border: 1px solid rgba(6, 150, 215, 0.2);
    border-radius: 12px;
    padding: 24px 28px;
    margin: 24px 0 32px;
}

.learning-objectives h3 {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 14px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.learning-objectives ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: grid;
    gap: 8px;
}

.learning-objectives li {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.9rem;
    color: var(--text);
    line-height: 1.5;
}

.learning-objectives li::before {
    content: "\2713";
    color: var(--green);
    font-weight: 700;
    flex-shrink: 0;
    margin-top: 1px;
}

/* ===== Key Takeaways ===== */
.key-takeaways {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.08), rgba(16, 185, 129, 0.02));
    border: 1px solid rgba(16, 185, 129, 0.2);
    border-radius: 12px;
    padding: 24px 28px;
    margin: 48px 0 24px;
}

.key-takeaways h3 {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--green);
    margin-bottom: 14px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.key-takeaways ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: grid;
    gap: 10px;
}

.key-takeaways li {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.9rem;
    color: var(--text);
    line-height: 1.6;
    padding-left: 4px;
}

.key-takeaways li::before {
    content: "\2605";
    color: var(--yellow);
    flex-shrink: 0;
    margin-top: 1px;
}

/* ===== Module TOC ===== */
.module-toc {
    position: fixed;
    top: 80px;
    right: 24px;
    width: 200px;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    z-index: 100;
    background: var(--bg-card);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
}

.module-toc h4 {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    margin-bottom: 12px;
    font-weight: 700;
}

.module-toc a {
    display: block;
    padding: 6px 10px;
    margin-bottom: 2px;
    font-size: 0.8rem;
    color: var(--text-muted);
    border-radius: 4px;
    text-decoration: none;
    transition: all 0.2s ease;
    line-height: 1.4;
    border-left: 2px solid transparent;
}

.module-toc a:hover {
    color: var(--text);
    background: var(--surface);
}

.module-toc a.active {
    color: var(--accent);
    border-left-color: var(--accent);
    background: var(--accent-glow);
    font-weight: 600;
}

/* Adjust main content to leave room for TOC on wide screens */
@media (min-width: 1200px) {
    .module-page .container {
        max-width: 900px;
        margin-right: 260px;
    }
}

@media (max-width: 1199px) {
    .module-toc {
        display: none;
    }
}

/* TOC scrollbar */
.module-toc::-webkit-scrollbar {
    width: 3px;
}
.module-toc::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

/* ===== Glossary Tooltip ===== */
.glossary-term {
    border-bottom: 1px dotted var(--accent);
    cursor: help;
    position: relative;
}

.glossary-tooltip {
    position: absolute;
    bottom: calc(100% + 8px);
    left: 50%;
    transform: translateX(-50%);
    background: rgba(14, 22, 38, 0.95);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 14px 18px;
    width: 280px;
    font-size: 0.82rem;
    line-height: 1.5;
    color: var(--text);
    box-shadow: 0 8px 32px rgba(0,0,0,0.3);
    z-index: 1000;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.2s var(--ease);
}

.glossary-term:hover .glossary-tooltip {
    opacity: 1;
}

.glossary-tooltip .tooltip-term {
    font-weight: 700;
    color: var(--accent);
    display: block;
    margin-bottom: 4px;
}

/* ===== Enhanced Concept Blocks ===== */
.concept-block {
    border-left: 4px solid var(--accent);
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.concept-block:hover {
    box-shadow: 0 2px 16px rgba(6, 150, 215, 0.1);
}

.concept-block h5 {
    position: relative;
    padding-left: 28px;
}

.concept-block h5::before {
    content: "◆";
    position: absolute;
    left: 0;
    color: var(--accent);
    font-size: 0.8em;
}

/* ===== Enhanced Feature Cards ===== */
.feature-card {
    transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(226, 162, 71, 0.1);
    border-color: rgba(226, 162, 71, 0.25);
}

.feature-card .feature-icon {
    transition: transform 0.3s ease;
}

.feature-card:hover .feature-icon {
    transform: scale(1.15);
}

/* ===== Enhanced Formula Box ===== */
.formula-box {
    background: var(--bg-card);
    border: 1px solid rgba(251, 191, 36, 0.15);
    border-left: 4px solid var(--yellow);
    border-radius: var(--radius);
    padding: 18px 22px;
    margin: 16px 0;
    font-family: var(--font-mono);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.formula-box .formula {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--yellow);
    margin-bottom: 8px;
}

.formula-box .formula-example {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-family: var(--font);
}

/* ===== Enhanced Tip Box ===== */
.tip-box {
    position: relative;
    padding-left: 48px;
}

.tip-box::before {
    content: "TIP";
    position: absolute;
    left: 12px;
    top: 16px;
    font-size: 0.6rem;
    font-weight: 800;
    letter-spacing: 0.05em;
    color: var(--accent);
    background: var(--accent-glow);
    padding: 2px 6px;
    border-radius: 3px;
}

/* ===== Enhanced Workflow Steps ===== */
.workflow-step {
    transition: background 0.2s ease, border-color 0.2s ease;
}

.workflow-step:hover {
    background: var(--surface);
    border-radius: 8px;
}

.step-num {
    transition: transform 0.2s ease, background 0.2s ease;
}

.workflow-step:hover .step-num {
    transform: scale(1.1);
    background: var(--accent);
    color: #fff;
}

/* ===== Smooth Section Transitions ===== */
.content-section {
    animation: fadeInUp 0.4s ease both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Stagger section animations */
.content-section:nth-child(1) { animation-delay: 0s; }
.content-section:nth-child(2) { animation-delay: 0.1s; }
.content-section:nth-child(3) { animation-delay: 0.2s; }
.content-section:nth-child(4) { animation-delay: 0.3s; }
.content-section:nth-child(5) { animation-delay: 0.4s; }

/* ===== Better Info Tables ===== */
.info-table {
    border-collapse: separate;
    border-spacing: 0;
}

.info-table thead th {
    position: sticky;
    top: 0;
    z-index: 1;
}

.info-table tbody tr {
    transition: background 0.15s ease;
}

.info-table tbody tr:hover {
    background: var(--accent-glow);
}

/* ===== Enhanced Model Viewer ===== */
.model-viewer-wrap {
    transition: box-shadow var(--transition);
    border-radius: var(--radius);
}

.model-viewer-wrap:hover {
    box-shadow: 0 8px 32px rgba(226, 162, 71, 0.15);
}

.model-caption {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 8px;
    font-style: italic;
}

/* ===== Comparison Grid Enhancement ===== */
.compare-item {
    transition: border-color 0.2s ease;
}

.compare-item:hover {
    border-color: var(--accent);
}

/* ===== Better Mobile Readability ===== */
@media (max-width: 768px) {
    .feature-grid {
        grid-template-columns: 1fr;
    }

    .comparison-grid {
        grid-template-columns: 1fr;
    }

    .module-badges {
        flex-wrap: wrap;
    }

    .glossary-grid {
        grid-template-columns: 1fr;
    }
}

/* ========================================
   Kolb's Experiential Learning Cycle
   ======================================== */

/* ===== Cycle Stage Indicator ===== */
.kolb-cycle {
    display: flex;
    gap: 4px;
    margin: 32px 0 40px;
    padding: 6px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    overflow: hidden;
}

.kolb-stage {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    transition: all var(--transition);
    cursor: default;
    position: relative;
    white-space: nowrap;
    overflow: hidden;
}

.kolb-stage .stage-num {
    width: 22px;
    height: 22px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.7rem;
    font-weight: 800;
    flex-shrink: 0;
    border: 1.5px solid var(--border);
    color: var(--text-muted);
    transition: all var(--transition);
}

.kolb-stage.active {
    background: var(--accent-dim);
    color: var(--accent);
}

.kolb-stage.active .stage-num {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
    box-shadow: 0 0 10px var(--accent-glow);
}

.kolb-stage.done {
    color: var(--green);
}

.kolb-stage.done .stage-num {
    background: var(--green);
    color: #fff;
    border-color: var(--green);
}

.kolb-stage .stage-label {
    overflow: hidden;
    text-overflow: ellipsis;
}

@media (max-width: 768px) {
    .kolb-cycle {
        flex-wrap: wrap;
    }
    .kolb-stage {
        flex: 1 1 45%;
        padding: 10px 12px;
        font-size: 0.72rem;
    }
}

/* ===== Stage 2: Reflection Prompts ===== */
.reflection-block {
    background: linear-gradient(135deg, rgba(139, 92, 246, 0.08), rgba(139, 92, 246, 0.02));
    border: 1px solid rgba(139, 92, 246, 0.18);
    border-radius: var(--radius);
    padding: 28px;
    margin: 40px 0;
    position: relative;
    overflow: hidden;
}

.reflection-block::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, #8b5cf6, transparent);
}

.reflection-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 18px;
    font-size: 1.05rem;
    font-weight: 700;
    color: #a78bfa;
}

.reflection-header .stage-badge {
    font-size: 0.65rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    padding: 3px 8px;
    border-radius: 100px;
    background: rgba(139, 92, 246, 0.15);
    color: #a78bfa;
}

.reflection-prompt {
    margin-bottom: 14px;
}

.reflection-prompt label {
    display: block;
    font-size: 0.92rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 8px;
    line-height: 1.5;
}

.reflection-prompt textarea {
    width: 100%;
    min-height: 72px;
    padding: 12px 16px;
    background: rgba(139, 92, 246, 0.05);
    border: 1px solid rgba(139, 92, 246, 0.15);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-family: var(--font);
    font-size: 0.9rem;
    line-height: 1.6;
    resize: vertical;
    outline: none;
    transition: border-color var(--transition);
}

.reflection-prompt textarea::placeholder {
    color: var(--text-muted);
    opacity: 0.7;
}

.reflection-prompt textarea:focus {
    border-color: #8b5cf6;
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

.reflection-saved {
    display: none;
    align-items: center;
    gap: 8px;
    padding: 10px 16px;
    background: rgba(34, 211, 160, 0.08);
    border: 1px solid rgba(34, 211, 160, 0.2);
    border-radius: var(--radius-sm);
    color: var(--green);
    font-size: 0.85rem;
    font-weight: 600;
    margin-top: 12px;
}

.reflection-saved.visible {
    display: flex;
}

/* ===== Stage 1 Enhancement: Challenge Mode ===== */
.challenge-banner {
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.1), rgba(251, 191, 36, 0.03));
    border: 1px solid rgba(251, 191, 36, 0.2);
    border-radius: var(--radius);
    padding: 20px 24px;
    margin-bottom: 20px;
    display: flex;
    align-items: flex-start;
    gap: 14px;
}

.challenge-banner .challenge-icon {
    font-size: 1.3rem;
    flex-shrink: 0;
    margin-top: 2px;
}

.challenge-banner .challenge-body h4 {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--yellow);
    margin-bottom: 4px;
}

.challenge-banner .challenge-body p {
    font-size: 0.88rem;
    color: var(--text-muted);
    margin: 0;
    line-height: 1.5;
}

.challenge-banner .challenge-body .challenge-target {
    display: inline-block;
    font-family: var(--font-mono);
    font-weight: 700;
    color: var(--yellow);
    background: rgba(251, 191, 36, 0.1);
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.85rem;
}

.challenge-result {
    text-align: center;
    padding: 12px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    margin-top: 12px;
    display: none;
}

.challenge-result.success {
    display: block;
    background: var(--green-bg);
    border: 1px solid rgba(34, 211, 160, 0.2);
    color: var(--green);
}

.challenge-result.hint {
    display: block;
    background: rgba(251, 191, 36, 0.08);
    border: 1px solid rgba(251, 191, 36, 0.2);
    color: var(--yellow);
}

/* ===== Stage 4: Experiment / Apply Blocks ===== */
.experiment-block {
    background: linear-gradient(135deg, rgba(226, 162, 71, 0.08), rgba(34, 211, 160, 0.04));
    border: 1px solid rgba(226, 162, 71, 0.18);
    border-radius: var(--radius);
    padding: 28px;
    margin: 40px 0;
    position: relative;
    overflow: hidden;
}

.experiment-block::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent), var(--green));
}

.experiment-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 16px;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--accent);
}

.experiment-header .stage-badge {
    font-size: 0.65rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    padding: 3px 8px;
    border-radius: 100px;
    background: var(--accent-dim);
    color: var(--accent);
}

.experiment-scenario {
    font-size: 0.95rem;
    color: var(--text);
    line-height: 1.6;
    margin-bottom: 16px;
}

.experiment-scenario strong {
    color: var(--accent);
}

.experiment-tasks {
    list-style: none;
    padding: 0;
    margin: 0 0 16px;
    display: grid;
    gap: 10px;
}

.experiment-tasks li {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.9rem;
    color: var(--text);
    line-height: 1.5;
    padding: 10px 14px;
    background: rgba(226, 162, 71, 0.04);
    border: 1px solid rgba(226, 162, 71, 0.1);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition);
}

.experiment-tasks li:hover {
    border-color: rgba(226, 162, 71, 0.25);
    background: rgba(226, 162, 71, 0.08);
}

.experiment-tasks li .task-check {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 2px solid var(--border);
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.7rem;
    transition: all var(--transition);
    margin-top: 1px;
}

.experiment-tasks li.checked .task-check {
    background: var(--green);
    border-color: var(--green);
    color: #fff;
}

.experiment-tasks li.checked {
    border-color: rgba(34, 211, 160, 0.2);
    color: var(--text-muted);
}

.experiment-progress {
    display: flex;
    align-items: center;
    gap: 12px;
    padding-top: 12px;
    border-top: 1px solid rgba(226, 162, 71, 0.1);
}

.experiment-progress-bar {
    flex: 1;
    height: 6px;
    background: var(--surface);
    border-radius: 100px;
    overflow: hidden;
}

.experiment-progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent), var(--green));
    border-radius: 100px;
    transition: width 0.5s var(--ease);
}

.experiment-progress-text {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    white-space: nowrap;
}

/* ===== Spaced Return Prompt ===== */
.spaced-return {
    background: var(--bg-card);
    border: 1px solid rgba(251, 191, 36, 0.15);
    border-radius: var(--radius);
    padding: 20px 24px;
    margin: 32px 0;
    display: none;
    align-items: center;
    gap: 14px;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.spaced-return.visible {
    display: flex;
}

.spaced-return-icon {
    font-size: 1.2rem;
    flex-shrink: 0;
}

.spaced-return-body {
    flex: 1;
}

.spaced-return-body strong {
    display: block;
    font-size: 0.9rem;
    color: var(--yellow);
    margin-bottom: 2px;
}

.spaced-return-body p {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin: 0;
}

.spaced-return .btn-small {
    flex-shrink: 0;
}

/* ===== Prediction Prompts (Productive Failure) ===== */
.prediction-prompt {
    background: linear-gradient(135deg, rgba(251, 146, 60, 0.08), rgba(251, 146, 60, 0.02));
    border: 1px solid rgba(251, 146, 60, 0.18);
    border-radius: var(--radius);
    padding: 22px 24px;
    margin-bottom: 20px;
    position: relative;
    overflow: hidden;
}

.prediction-prompt::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, #fb923c, transparent);
}

.prediction-prompt .pred-header {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: #fb923c;
    margin-bottom: 10px;
}

.prediction-prompt .pred-question {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 12px;
    line-height: 1.5;
}

.prediction-options {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 8px;
}

.prediction-options button {
    padding: 8px 18px;
    border: 1.5px solid rgba(251, 146, 60, 0.25);
    border-radius: var(--radius-sm);
    background: rgba(251, 146, 60, 0.05);
    color: var(--text);
    font-size: 0.88rem;
    font-weight: 500;
    cursor: pointer;
    font-family: var(--font);
    transition: all var(--transition);
}

.prediction-options button:hover {
    border-color: #fb923c;
    background: rgba(251, 146, 60, 0.12);
}

.prediction-options button.selected {
    border-color: #fb923c;
    background: rgba(251, 146, 60, 0.15);
    color: #fb923c;
    font-weight: 600;
}

.prediction-options button.correct {
    border-color: var(--green);
    background: var(--green-bg);
    color: var(--green);
}

.prediction-options button.incorrect {
    border-color: var(--red);
    background: var(--red-bg);
    color: var(--red);
    opacity: 0.7;
}

.prediction-options button:disabled {
    cursor: default;
}

.prediction-feedback {
    display: none;
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.88rem;
    line-height: 1.5;
    margin-top: 10px;
}

.prediction-feedback.visible {
    display: block;
}

.prediction-feedback.correct {
    background: var(--green-bg);
    border: 1px solid rgba(34, 211, 160, 0.2);
    color: var(--green);
}

.prediction-feedback.incorrect {
    background: rgba(251, 146, 60, 0.08);
    border: 1px solid rgba(251, 146, 60, 0.2);
    color: #fb923c;
}

/* ===== Collapsible Domain Reference Panel ===== */
.demo-reference {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    margin-bottom: 16px;
    overflow: hidden;
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.demo-reference-toggle {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: 14px 18px;
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    font-family: var(--font);
    text-align: left;
    transition: color var(--transition);
}

.demo-reference-toggle:hover {
    color: var(--text);
}

.demo-reference-toggle .ref-icon {
    font-size: 0.75rem;
    transition: transform var(--transition);
}

.demo-reference.open .demo-reference-toggle .ref-icon {
    transform: rotate(90deg);
}

.demo-reference-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s var(--ease);
}

.demo-reference.open .demo-reference-content {
    max-height: 600px;
}

.demo-reference-content-inner {
    padding: 0 18px 16px;
    font-size: 0.88rem;
    line-height: 1.6;
    color: var(--text-muted);
}

.demo-reference-content-inner strong {
    color: var(--text);
}

.demo-reference-content-inner p {
    margin-bottom: 8px;
}

.demo-reference-content-inner code {
    font-family: var(--font-mono);
    background: var(--surface);
    padding: 1px 6px;
    border-radius: 3px;
    font-size: 0.85em;
}

/* ===== Simulation Inquiry Tasks ===== */
.sim-inquiry {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px 18px;
    margin-top: 16px;
}

.sim-inquiry h5 {
    font-size: 0.82rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--accent);
    margin-bottom: 10px;
}

.sim-inquiry ol {
    padding-left: 20px;
    margin: 0;
}

.sim-inquiry li {
    font-size: 0.88rem;
    color: var(--text);
    line-height: 1.5;
    padding: 4px 0;
}

.sim-inquiry li::marker {
    color: var(--accent);
    font-weight: 700;
}