/* ===== CSS Variables & Reset ===== */
:root {
    --bg-primary: #0a0e17;
    --bg-secondary: #111827;
    --bg-card: #1a2236;
    --bg-card-hover: #1f2a40;
    --text-primary: #e8eaf0;
    --text-secondary: #9ca3af;
    --text-muted: #6b7280;
    --accent-blue: #3b82f6;
    --accent-blue-dim: #1e40af;
    --accent-green: #10b981;
    --accent-green-dim: #065f46;
    --accent-orange: #f59e0b;
    --accent-orange-dim: #92400e;
    --accent-purple: #8b5cf6;
    --accent-red: #ef4444;
    --accent-red-dim: #7f1d1d;
    --accent-cyan: #06b6d4;
    --border-color: #2d3748;
    --border-light: #374151;
    --shadow: 0 4px 20px rgba(0,0,0,0.3);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.3s ease;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --nav-height: 64px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

/* ===== Navigation ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background: rgba(10, 14, 23, 0.92);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    display: flex;
    align-items: center;
    padding: 0 2rem;
}

.nav-brand {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--accent-blue);
    text-decoration: none;
    white-space: nowrap;
    margin-right: 2rem;
    letter-spacing: -0.02em;
}

.nav-brand span {
    color: var(--text-muted);
    font-weight: 400;
    font-size: 0.85rem;
    margin-left: 0.5rem;
}

.nav-links {
    display: flex;
    gap: 0.25rem;
    list-style: none;
    flex: 1;
    justify-content: center;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
    transition: var(--transition);
    white-space: nowrap;
}

.nav-links a:hover {
    color: var(--text-primary);
    background: var(--bg-card);
}

.nav-links a.active {
    color: var(--accent-blue);
    background: rgba(59, 130, 246, 0.1);
}

.nav-hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 8px;
    background: none;
    border: none;
}

.nav-hamburger span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-secondary);
    transition: var(--transition);
}

/* ===== Main Content ===== */
.main-content {
    margin-top: var(--nav-height);
    min-height: calc(100vh - var(--nav-height));
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.container-wide {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

.container-narrow {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
}

/* ===== Hero Section ===== */
.hero {
    text-align: center;
    padding: 4rem 2rem;
    background: linear-gradient(180deg, rgba(59,130,246,0.08) 0%, transparent 100%);
    border-bottom: 1px solid var(--border-color);
}

.hero h1 {
    font-size: 2.5rem;
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.03em;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero .subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto 1.5rem;
}

.hero .authors {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.hero .journal-badge {
    display: inline-block;
    background: rgba(59,130,246,0.15);
    color: var(--accent-blue);
    padding: 0.3rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

/* ===== Section Headers ===== */
.section-header {
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.section-header h2 {
    font-size: 1.75rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin: 2rem 0 1rem;
    color: var(--text-primary);
}

h4 {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 1.5rem 0 0.75rem;
    color: var(--accent-blue);
}

/* ===== Cards ===== */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    transition: var(--transition);
}

.card:hover {
    border-color: var(--border-light);
    background: var(--bg-card-hover);
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.card-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.card-title .icon {
    width: 28px;
    height: 28px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.85rem;
    flex-shrink: 0;
}

.icon-blue { background: rgba(59,130,246,0.15); color: var(--accent-blue); }
.icon-green { background: rgba(16,185,129,0.15); color: var(--accent-green); }
.icon-orange { background: rgba(245,158,11,0.15); color: var(--accent-orange); }
.icon-purple { background: rgba(139,92,246,0.15); color: var(--accent-purple); }
.icon-red { background: rgba(239,68,68,0.15); color: var(--accent-red); }
.icon-cyan { background: rgba(6,182,212,0.15); color: var(--accent-cyan); }

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.6rem 1.2rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    border: 1px solid transparent;
    transition: var(--transition);
    text-decoration: none;
    font-family: var(--font-sans);
}

.btn-primary {
    background: var(--accent-blue);
    color: white;
}

.btn-primary:hover {
    background: #2563eb;
    box-shadow: 0 0 20px rgba(59,130,246,0.3);
}

.btn-secondary {
    background: transparent;
    color: var(--text-secondary);
    border-color: var(--border-color);
}

.btn-secondary:hover {
    color: var(--text-primary);
    border-color: var(--border-light);
    background: var(--bg-card);
}

.btn-success {
    background: var(--accent-green);
    color: white;
}

.btn-success:hover {
    background: #059669;
}

.btn-warning {
    background: var(--accent-orange);
    color: #1a1a1a;
}

.btn-danger {
    background: var(--accent-red);
    color: white;
}

.btn-group {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

/* ===== Task Experiment Area ===== */
.experiment-container {
    display: flex;
    gap: 2rem;
    align-items: flex-start;
}

.experiment-panel {
    flex: 1;
    min-width: 0;
}

.experiment-display {
    background: #000;
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    position: relative;
    width: 100%;
    aspect-ratio: 1;
    max-width: 600px;
    margin: 0 auto;
    overflow: hidden;
}

.experiment-controls {
    width: 320px;
    flex-shrink: 0;
}

.control-group {
    margin-bottom: 1.25rem;
}

.control-group label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.4rem;
}

.control-group select,
.control-group input[type="range"] {
    width: 100%;
    padding: 0.5rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-family: var(--font-sans);
}

input[type="range"] {
    -webkit-appearance: none;
    height: 6px;
    background: var(--border-color);
    border-radius: 3px;
    border: none;
    padding: 0;
}

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

.range-value {
    font-size: 0.8rem;
    color: var(--accent-blue);
    font-weight: 600;
    float: right;
}

/* ===== Stats Display ===== */
.stats-row {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.stat-box {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 1rem;
    flex: 1;
    min-width: 120px;
    text-align: center;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-blue);
    font-family: var(--font-mono);
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-top: 0.25rem;
}

/* ===== Charts/Graphs ===== */
.chart-container {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

.chart-title {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.chart-canvas {
    width: 100%;
    height: 350px;
    position: relative;
    overflow: hidden;
}

.chart-canvas canvas {
    display: block;
}

/* ===== Paper Content ===== */
.paper-body {
    font-size: 1rem;
    line-height: 1.85;
    color: var(--text-primary);
}

.paper-body p {
    margin-bottom: 1.25rem;
    text-align: justify;
}

.paper-body h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin: 2.5rem 0 1rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
    color: var(--accent-blue);
}

.paper-body h3 {
    font-size: 1.2rem;
    margin: 2rem 0 0.75rem;
    color: var(--accent-purple);
}

.figure-container {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 2rem 0;
    text-align: center;
}

.figure-container img,
.figure-container svg {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-sm);
    margin-bottom: 1rem;
}

.figure-caption {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-align: left;
    line-height: 1.6;
}

.figure-caption strong {
    color: var(--text-primary);
}

/* ===== Interactive Parameter Panels ===== */
.param-panel {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.25rem;
    margin-bottom: 1.5rem;
}

.param-row {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 0.75rem;
}

.param-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    min-width: 160px;
    flex-shrink: 0;
}

.param-slider {
    flex: 1;
}

.param-value-display {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--accent-cyan);
    min-width: 60px;
    text-align: right;
}

/* ===== Tabs ===== */
.tab-group {
    display: flex;
    gap: 0.25rem;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 1.5rem;
    overflow-x: auto;
}

.tab-btn {
    padding: 0.6rem 1.2rem;
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: var(--transition);
    white-space: nowrap;
    font-family: var(--font-sans);
}

.tab-btn:hover {
    color: var(--text-secondary);
}

.tab-btn.active {
    color: var(--accent-blue);
    border-bottom-color: var(--accent-blue);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* ===== Code Blocks ===== */
.code-block {
    background: #0d1117;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 1rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.6;
    overflow-x: auto;
    margin: 1rem 0;
    color: #c9d1d9;
}

/* ===== Tables ===== */
.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
    margin: 1rem 0;
}

.data-table th {
    background: var(--bg-secondary);
    color: var(--text-secondary);
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
    padding: 0.75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.data-table td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
}

.data-table tr:hover td {
    background: var(--bg-card);
}

/* ===== Badges ===== */
.badge {
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
}

.badge-blue { background: rgba(59,130,246,0.15); color: var(--accent-blue); }
.badge-green { background: rgba(16,185,129,0.15); color: var(--accent-green); }
.badge-orange { background: rgba(245,158,11,0.15); color: var(--accent-orange); }
.badge-purple { background: rgba(139,92,246,0.15); color: var(--accent-purple); }
.badge-red { background: rgba(239,68,68,0.15); color: var(--accent-red); }

/* ===== Callout Boxes ===== */
.callout {
    border-left: 3px solid var(--accent-blue);
    background: rgba(59,130,246,0.05);
    padding: 1rem 1.25rem;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    margin: 1.5rem 0;
}

.callout-green { border-color: var(--accent-green); background: rgba(16,185,129,0.05); }
.callout-orange { border-color: var(--accent-orange); background: rgba(245,158,11,0.05); }
.callout-purple { border-color: var(--accent-purple); background: rgba(139,92,246,0.05); }

.callout-title {
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

/* ===== Progress Bar ===== */
.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin: 0.5rem 0;
}

.progress-fill {
    height: 100%;
    background: var(--accent-blue);
    border-radius: 4px;
    transition: width 0.5s ease;
}

/* ===== Footer ===== */
.footer {
    text-align: center;
    padding: 2rem;
    border-top: 1px solid var(--border-color);
    margin-top: 3rem;
    color: var(--text-muted);
    font-size: 0.85rem;
}

.footer a {
    color: var(--accent-blue);
    text-decoration: none;
}

.footer a:hover {
    text-decoration: underline;
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--border-light); }

/* ===== Responsive ===== */
@media (max-width: 1024px) {
    .experiment-container {
        flex-direction: column;
    }
    .experiment-controls {
        width: 100%;
    }
}

@media (max-width: 768px) {
    .navbar { padding: 0 1rem; }
    .nav-links { 
        display: none;
        position: absolute;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: var(--bg-primary);
        border-bottom: 1px solid var(--border-color);
        flex-direction: column;
        padding: 1rem;
    }
    .nav-links.open { display: flex; }
    .nav-hamburger { display: flex; }
    .nav-brand span { display: none; }
    .hero h1 { font-size: 1.75rem; }
    .container, .container-wide, .container-narrow { padding: 1rem; }
    .card-grid { grid-template-columns: 1fr; }
    .stats-row { flex-direction: column; }
    .param-row { flex-direction: column; align-items: flex-start; }
}

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

.fade-in {
    animation: fadeIn 0.5s ease forwards;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.pulse { animation: pulse 2s infinite; }

/* ===== Tooltip ===== */
.tooltip {
    position: relative;
    cursor: help;
    border-bottom: 1px dashed var(--text-muted);
}

.tooltip::after {
    content: attr(data-tip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--bg-card);
    color: var(--text-primary);
    padding: 0.5rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s;
    border: 1px solid var(--border-color);
    z-index: 100;
}

.tooltip:hover::after {
    opacity: 1;
}

/* ===== References ===== */
.reference-list {
    font-size: 0.85rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

.reference-list li {
    margin-bottom: 0.5rem;
    padding-left: 0.5rem;
}

/* ===== Inline equation approximation ===== */
.eq {
    font-family: var(--font-mono);
    font-size: 0.9em;
    color: var(--accent-cyan);
    background: rgba(6,182,212,0.08);
    padding: 0.1em 0.4em;
    border-radius: 4px;
}

/* ===== Two column layout ===== */
.two-col {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 768px) {
    .two-col { grid-template-columns: 1fr; }
}

/* ===== Link styles ===== */
a {
    color: var(--accent-blue);
    text-decoration: none;
    transition: var(--transition);
}
a:hover {
    text-decoration: underline;
}

/* ===== Trial feedback ===== */
.feedback-correct {
    color: var(--accent-green);
    font-weight: 700;
}
.feedback-incorrect {
    color: var(--accent-red);
    font-weight: 700;
}

/* ===== Loading spinner ===== */
.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--accent-blue);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 2rem auto;
}

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

/* ===== Legend ===== */
.legend {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
    font-size: 0.8rem;
    margin: 0.75rem 0;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.legend-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    flex-shrink: 0;
}

/* Task page specific */
.task-description {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1rem 1.25rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.trial-indicator {
    text-align: center;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}