/* CReA - Coding Reliability Assessment */
/* Nike-inspired: negro/gris/blanco */

:root {
    --primary: #111111;
    --white: #FFFFFF;
    --text: #111111;
    --text-secondary: #767676;
    --border: #E5E5E5;
    --bg: #FFFFFF;
    --bg-secondary: #F5F5F5;
    --success: #128A09;
    --error: #D32F2F;
    --warning: #C77C00;
    --gray-50: #FAFAFA;
    --gray-100: #F5F5F5;
    --gray-200: #EEEEEE;
    --gray-300: #E0E0E0;
    --gray-400: #BDBDBD;
    --gray-600: #757575;
    --gray-800: #424242;
    --radius: 0px;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
    --transition: all 0.2s ease;
    --navbar-h: 60px;
}

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

body {
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* ==================== NAVBAR ==================== */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
    height: var(--navbar-h);
    border-bottom: 1px solid var(--border);
    background: var(--bg);
    position: sticky;
    top: 0;
    z-index: 100;
    flex-shrink: 0;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
    letter-spacing: 0.15em;
    text-transform: uppercase;
}

.nav-links { display: flex; align-items: center; gap: 1.5rem; }
.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 500;
    letter-spacing: 0.02em;
    transition: var(--transition);
}
.nav-links a:hover { color: var(--primary); }
.nav-user {
    color: var(--text-secondary);
    font-size: 0.8rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* ==================== MAIN CONTAINER ==================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
    flex: 1;
}

/* ==================== BUTTONS ==================== */
.btn {
    display: inline-block;
    padding: 0.5rem 1.25rem;
    border: 1.5px solid var(--primary);
    border-radius: var(--radius);
    background: var(--bg);
    color: var(--primary);
    text-decoration: none;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    cursor: pointer;
    transition: var(--transition);
}
.btn:hover { background: var(--primary); color: var(--white); }

.btn-primary { background: var(--primary); color: var(--white); border-color: var(--primary); }
.btn-primary:hover { background: #333333; border-color: #333333; color: var(--white); }

.btn-sm { padding: 0.3rem 0.75rem; font-size: 0.7rem; }
.btn-danger { background: var(--error); color: var(--white); border-color: var(--error); }
.btn-danger:hover { background: #B71C1C; border-color: #B71C1C; }
.btn-danger-outline { background: transparent; color: var(--error); border: 1px solid var(--error); padding: 0.2rem 0.5rem; font-size: 0.7rem; cursor: pointer; font-weight: 600; }
.btn-danger-outline:hover { background: var(--error); color: var(--white); }
.btn-lg { padding: 0.75rem 2.5rem; font-size: 0.85rem; }
.btn-block { display: block; width: 100%; text-align: center; margin-top: 0.5rem; }

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

/* ==================== HERO (Landing) ==================== */
.hero { text-align: center; padding: 6rem 0 3rem; }
.hero h1 { font-size: 4rem; font-weight: 900; letter-spacing: 0.2em; color: var(--primary); text-transform: uppercase; }
.hero .subtitle { font-size: 1rem; color: var(--text-secondary); margin-top: 0.75rem; letter-spacing: 0.1em; text-transform: uppercase; font-weight: 500; }
.hero-actions { margin-top: 2.5rem; }

/* Info section */
.info-section { max-width: 750px; margin: 4rem auto; text-align: center; }
.info-section h2 { font-size: 1.5rem; font-weight: 700; margin-bottom: 1rem; text-transform: uppercase; letter-spacing: 0.05em; }
.info-section p { color: var(--text-secondary); font-size: 0.95rem; line-height: 1.7; }

.features { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.5rem; margin-top: 2.5rem; text-align: left; }
.feature { padding: 1.5rem; border: 1px solid var(--border); transition: var(--transition); }
.feature:hover { border-color: var(--primary); }
.feature h3 { font-size: 0.85rem; font-weight: 700; margin-bottom: 0.5rem; text-transform: uppercase; letter-spacing: 0.03em; }
.feature p { font-size: 0.85rem; color: var(--text-secondary); line-height: 1.5; }

/* ==================== AUTH CARD (Login) ==================== */
.auth-card { max-width: 420px; margin: 5rem auto; padding: 2.5rem; border: 1px solid var(--border); }
.auth-card h2 { margin-bottom: 2rem; text-align: center; font-size: 1.25rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em; }

/* ==================== FORMS ==================== */
.form-group { margin-bottom: 1rem; }
.form-group label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 0.4rem;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    color: var(--text);
}
.form-group input[type="text"],
.form-group input[type="password"],
.form-group input[type="email"],
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.6rem 0.75rem;
    border: 1.5px solid var(--border);
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-family: inherit;
    background: var(--bg);
    transition: var(--transition);
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 1px var(--primary);
}

.checkbox-group { display: flex; align-items: center; gap: 0.5rem; }
.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    cursor: pointer;
    font-size: 0.875rem;
    padding: 0.5rem 0;
}
.checkbox-label input[type="checkbox"] { width: 18px; height: 18px; accent-color: var(--primary); cursor: pointer; }

.help-text { display: block; font-size: 0.75rem; color: var(--text-secondary); margin-top: 0.25rem; }
.field-error { color: var(--error); font-size: 0.75rem; margin-top: 0.25rem; font-weight: 500; }

/* Radio groups */
.form-group ul { list-style: none; padding: 0; }
.form-group ul li { padding: 0.25rem 0; }
.form-group ul li label {
    display: flex; align-items: center; gap: 0.5rem;
    font-size: 0.875rem; font-weight: 400; text-transform: none; letter-spacing: 0; cursor: pointer;
}
.form-group ul li label input[type="radio"] { accent-color: var(--primary); }

/* Technique tags */
.technique-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-top: 0.5rem;
}
.technique-tag {
    display: inline-block;
    padding: 0.25rem 0.6rem;
    background: var(--gray-100);
    border: 1px solid var(--border);
    font-size: 0.75rem;
    cursor: pointer;
    transition: var(--transition);
    user-select: none;
}
.technique-tag:hover { border-color: var(--primary); }
.technique-tag.selected { background: var(--primary); color: var(--white); border-color: var(--primary); }

/* Conditional field hide */
.field-hidden { display: none !important; }

/* ==================== TABLE ==================== */
.table { width: 100%; border-collapse: collapse; margin: 1.5rem 0; font-size: 0.85rem; }
.table th, .table td { padding: 0.75rem 1rem; border-bottom: 1px solid var(--border); text-align: left; }
.table th {
    font-size: 0.7rem; font-weight: 700; text-transform: uppercase;
    letter-spacing: 0.08em; color: var(--text-secondary);
    border-bottom: 2px solid var(--primary); padding-bottom: 0.5rem;
}
.table tr:hover { background: var(--gray-50); }
.title-cell { max-width: 280px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* Row status */
.row-completed { }
.row-in_progress { }
.row-disagreement { background: #FFF5F5; }
.cell-diff { background: #FFE0E0; font-weight: 600; }

/* ==================== BADGES ==================== */
.badge { display: inline-block; padding: 0.2rem 0.6rem; font-size: 0.65rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; }
.badge-success { background: var(--primary); color: var(--white); }
.badge-warning { background: var(--gray-200); color: var(--text); }
.badge-neutral { background: var(--gray-100); color: var(--text-secondary); }

/* ==================== PROGRESS BAR ==================== */
.progress-section { margin-bottom: 2rem; }
.progress-bar-container { width: 100%; height: 4px; background: var(--gray-200); overflow: hidden; margin: 1rem 0; }
.progress-bar { height: 100%; background: var(--primary); font-size: 0; transition: width 0.3s; }

.stats { display: flex; gap: 2.5rem; margin-bottom: 1.5rem; font-size: 0.85rem; color: var(--text-secondary); }
.stats .stat strong { color: var(--primary); font-weight: 700; }

/* ==================== CODING LAYOUT (3 columns) ==================== */
.coding-layout {
    display: grid;
    grid-template-columns: 280px 1fr 40%;
    gap: 0;
    min-height: calc(100vh - var(--navbar-h));
    /* No negative margins — use full_content block instead */
}

/* Sidebar */
.coding-sidebar {
    border-right: 1px solid var(--border);
    padding: 1.5rem 1.25rem;
    background: var(--gray-50);
    overflow-y: auto;
    height: calc(100vh - var(--navbar-h));
    position: sticky;
    top: var(--navbar-h);
}
.coding-sidebar h3 { font-size: 0.9rem; font-weight: 700; margin-bottom: 0.25rem; }
.text-muted { color: var(--text-secondary); font-size: 0.8rem; }

.sidebar-study-info { margin-bottom: 1rem; }

.step-nav { margin-top: 0.5rem; }
.step-nav-label {
    font-size: 0.65rem; font-weight: 700; text-transform: uppercase;
    letter-spacing: 0.08em; color: var(--text-secondary); margin-bottom: 0.5rem;
}
.step-link {
    display: flex; align-items: center; gap: 0.5rem;
    padding: 0.45rem 0.75rem; margin-bottom: 0.15rem;
    text-decoration: none; color: var(--text-secondary); font-size: 0.78rem;
    font-weight: 500; border-left: 3px solid transparent; transition: var(--transition);
}
.step-num {
    display: inline-flex; align-items: center; justify-content: center;
    width: 20px; height: 20px; border-radius: 50%;
    background: var(--gray-200); color: var(--text-secondary);
    font-size: 0.65rem; font-weight: 700; flex-shrink: 0;
}
.step-link.active { background: var(--white); color: var(--primary); border-left-color: var(--primary); font-weight: 700; }
.step-link.active .step-num { background: var(--primary); color: var(--white); }
.step-link.done { color: var(--success); }
.step-link.done .step-num { background: var(--success); color: var(--white); }
.step-link.disabled { opacity: 0.35; pointer-events: none; }
.step-link:hover:not(.disabled) { background: var(--white); color: var(--primary); }

/* Guide section in sidebar — improved UX */
.sidebar-guide {
    margin-top: 1.5rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border);
}
.sidebar-guide h4 {
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}
.sidebar-guide > p,
.sidebar-guide > ul {
    font-size: 0.75rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 0.5rem;
}
.sidebar-guide ul {
    list-style: none;
    padding: 0;
}
.sidebar-guide li {
    padding: 0.2rem 0;
    padding-left: 0.75rem;
    border-left: 2px solid var(--gray-300);
    margin-bottom: 0.15rem;
}
.sidebar-guide li strong {
    color: var(--text);
    font-weight: 600;
}
.sidebar-guide code {
    font-size: 0.7rem;
    background: var(--white);
    padding: 0.1rem 0.3rem;
    border: 1px solid var(--border);
    font-family: 'SF Mono', monospace;
}
.sidebar-guide .guide-note {
    background: var(--white);
    border: 1px solid var(--border);
    padding: 0.6rem 0.75rem;
    font-size: 0.72rem;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-top: 0.75rem;
}
.sidebar-guide .guide-note strong {
    color: var(--primary);
}

/* Main form area */
.coding-main {
    padding: 2rem 2.5rem;
    overflow-y: auto;
    height: calc(100vh - var(--navbar-h));
}
.coding-form { max-width: 600px; }

.step-header { margin-bottom: 1.5rem; }
.step-badge {
    display: inline-block; padding: 0.2rem 0.6rem; background: var(--primary);
    color: var(--white); font-size: 0.65rem; font-weight: 700;
    text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 0.5rem;
}
.step-header h2 { font-size: 1.25rem; font-weight: 700; }

.form-actions { display: flex; gap: 0.75rem; margin-top: 2rem; padding-top: 1.25rem; border-top: 1px solid var(--border); }

/* Summary box */
.summary-box { padding: 1.25rem; background: var(--gray-50); border: 1px solid var(--border); margin: 1.5rem 0; }
.summary-box h3 { font-size: 0.75rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 0.75rem; }
.summary-box p { font-size: 0.85rem; margin-bottom: 0.3rem; }

/* PDF panel */
.coding-pdf {
    border-left: 1px solid var(--border);
    background: var(--gray-100);
    display: flex;
    flex-direction: column;
    position: sticky;
    top: var(--navbar-h);
    height: calc(100vh - var(--navbar-h));
}
.pdf-header {
    padding: 0.75rem 1rem; border-bottom: 1px solid var(--border);
    display: flex; justify-content: space-between; align-items: center;
    background: var(--bg); flex-shrink: 0;
}
.pdf-header span { font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; color: var(--text-secondary); }
.pdf-actions { display: flex; gap: 0.5rem; }
.pdf-actions a { font-size: 0.7rem; color: var(--text-secondary); text-decoration: none; padding: 0.2rem 0.5rem; border: 1px solid var(--border); transition: var(--transition); }
.pdf-actions a:hover { border-color: var(--primary); color: var(--primary); }
.pdf-embed { flex: 1; width: 100%; border: none; }
.pdf-placeholder { flex: 1; display: flex; align-items: center; justify-content: center; color: var(--text-secondary); font-size: 0.9rem; }

/* ==================== METRIC CARDS ==================== */
.metric-cards { display: flex; gap: 1.5rem; margin: 1.5rem 0; }
.metric-card { display: flex; flex-direction: column; align-items: center; padding: 1.5rem 2rem; border: 1px solid var(--border); min-width: 180px; transition: var(--transition); }
.metric-card:hover { border-color: var(--primary); }
.metric-value { font-size: 2.25rem; font-weight: 900; color: var(--primary); }
.metric-label { font-size: 0.7rem; font-weight: 600; color: var(--text-secondary); margin-top: 0.25rem; text-align: center; text-transform: uppercase; letter-spacing: 0.05em; }

.report-summary { margin-top: 2rem; }
.inline-form { display: inline; }

/* ==================== ALERTS ==================== */
.alert { padding: 0.75rem 1rem; margin-bottom: 1rem; font-size: 0.85rem; border: 1px solid; }
.alert-error { background: #FFF5F5; border-color: var(--error); color: var(--error); }
.alert-success { background: #F0FFF0; border-color: var(--success); color: var(--success); }

/* ==================== FOOTER ==================== */
footer {
    border-top: 1px solid var(--border);
    margin-top: auto;
    background: var(--bg);
    padding: 1.25rem 2rem;
}
.footer-content {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1.5rem;
    font-size: 0.75rem;
    color: var(--text-secondary);
}
.footer-content a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
}
.footer-content a:hover { color: var(--primary); }
.icon-heart {
    width: 14px;
    height: 14px;
    color: var(--error);
    vertical-align: -2px;
    display: inline-block;
}
.footer-social {
    display: flex;
    gap: 0.75rem;
    align-items: center;
}
.footer-social a {
    display: flex;
    align-items: center;
    color: var(--text-secondary);
}
.footer-social a:hover { color: var(--primary); }
.footer-social svg { width: 18px; height: 18px; }

/* ==================== PAGE HEADERS ==================== */
h1 { font-size: 1.75rem; font-weight: 800; letter-spacing: 0.02em; margin-bottom: 0.5rem; }
h2 { font-size: 1.25rem; font-weight: 700; }
h3 { font-size: 1rem; font-weight: 700; }

section { margin-bottom: 2.5rem; }
section h2 { text-transform: uppercase; letter-spacing: 0.05em; font-size: 1rem; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--primary); }

/* Guide page lists */
section ul { padding-left: 0; list-style: none; }
section ul li { padding: 0.35rem 0; font-size: 0.875rem; border-bottom: 1px solid var(--gray-100); }
section ul li strong { font-weight: 700; }
section ul li code { font-size: 0.8rem; background: var(--gray-100); padding: 0.1rem 0.4rem; border: 1px solid var(--border); font-family: 'SF Mono', monospace; }

/* ==================== RESPONSIVE ==================== */
@media (max-width: 1200px) {
    .coding-layout { grid-template-columns: 260px 1fr; }
    .coding-pdf { display: none; }
    .pdf-fallback-links { display: flex !important; }
}

@media (max-width: 768px) {
    .features { grid-template-columns: 1fr; }
    .coding-layout { grid-template-columns: 1fr; }
    .coding-sidebar { position: static; height: auto; border-right: none; border-bottom: 1px solid var(--border); }
    .coding-main { height: auto; }
    .stats { flex-wrap: wrap; gap: 1rem; }
    .metric-cards { flex-wrap: wrap; }
    .hero h1 { font-size: 2.5rem; }
    .navbar { padding: 0 1rem; }
    .footer-content { flex-direction: column; gap: 0.5rem; }
}

/* PDF fallback links (visible when PDF panel hidden) */
.pdf-fallback-links { display: none; gap: 0.5rem; margin-top: 0.75rem; }

/* ==================== METRIC COLOR CODING ==================== */
.metric-good { color: var(--success) !important; }
.metric-warn { color: var(--warning) !important; }
.metric-bad { color: var(--error) !important; }
.cell-good { background: #F0FFF0; }
.cell-warn { background: #FFFDE7; }
.cell-bad { background: #FFF5F5; }

/* Reference badge */
.badge-ref { background: var(--success); color: var(--white); margin-left: 0.3rem; font-size: 0.6rem; }
.row-reference { background: #F0FFF0; }

/* Chart containers */
.chart-container { border: 1px solid var(--border); padding: 1rem; background: var(--bg); }

/* ==================== DASHBOARD PI ==================== */
.dashboard-cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; margin-bottom: 2rem; }
.dash-card { padding: 1.25rem; border: 1px solid var(--border); text-align: center; transition: var(--transition); }
.dash-card:hover { border-color: var(--primary); }
.dash-card .dash-value { font-size: 2rem; font-weight: 900; color: var(--primary); display: block; }
.dash-card .dash-label { font-size: 0.7rem; font-weight: 600; color: var(--text-secondary); text-transform: uppercase; letter-spacing: 0.05em; }

.pi-actions { display: flex; gap: 0.75rem; margin-bottom: 2rem; flex-wrap: wrap; }

@media (max-width: 768px) {
    .dashboard-cards { grid-template-columns: repeat(2, 1fr); }
}

/* ==================== PAPER DRAFT LAYOUT ==================== */
.paper-layout {
    display: grid;
    grid-template-columns: 240px 1fr 300px;
    gap: 0;
    min-height: calc(100vh - var(--navbar-h));
}

.paper-toc {
    border-right: 1px solid var(--border);
    padding: 1.5rem 1.25rem;
    background: var(--gray-50);
    overflow-y: auto;
    height: calc(100vh - var(--navbar-h));
    position: sticky;
    top: var(--navbar-h);
}
.paper-toc h3 { font-size: 0.9rem; font-weight: 700; margin-bottom: 0.25rem; }
.paper-toc-links { display: flex; flex-direction: column; gap: 0.15rem; }
.paper-toc-links a { font-size: 0.78rem; color: var(--text-secondary); text-decoration: none; padding: 0.3rem 0.75rem; border-left: 3px solid transparent; transition: var(--transition); }
.paper-toc-links a:hover { color: var(--primary); border-left-color: var(--primary); background: var(--white); }

.paper-content {
    padding: 2rem 2.5rem;
    overflow-y: auto;
    height: calc(100vh - var(--navbar-h));
    line-height: 1.8;
    font-size: 0.9rem;
}
.paper-content h1 { font-size: 1.5rem; margin: 2rem 0 1rem; font-weight: 800; letter-spacing: -0.01em; border-bottom: 2px solid var(--primary); padding-bottom: 0.5rem; }
.paper-content h2 { font-size: 1.15rem; margin: 1.5rem 0 0.75rem; font-weight: 700; color: var(--text); }
.paper-content h3 { font-size: 1rem; margin: 1.25rem 0 0.5rem; font-weight: 600; }

/* Paper tables */
.paper-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    font-size: 0.8rem;
    line-height: 1.5;
}
.paper-table td, .paper-table th {
    border: 1px solid var(--border);
    padding: 0.5rem 0.75rem;
    text-align: left;
    vertical-align: top;
}
.paper-table tr:first-child td,
.paper-table thead td,
.paper-table thead th {
    background: var(--primary);
    color: var(--white);
    font-weight: 700;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}
.paper-table tr:nth-child(even) td { background: var(--gray-50); }
.paper-table tr:hover td { background: var(--gray-100); }
.paper-table tr:first-child:hover td { background: var(--primary); }

/* Paper figures */
.paper-figure {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 1.5rem auto;
    border: 1px solid var(--border);
    padding: 0.5rem;
    background: var(--white);
}

.commentable {
    cursor: pointer;
    padding: 0.25rem 0.5rem;
    margin: 0 -0.5rem;
    border-left: 3px solid transparent;
    transition: var(--transition);
    position: relative;
}
.commentable:hover { background: var(--gray-50); border-left-color: var(--gray-400); }

.comment-badge {
    position: absolute;
    right: -0.5rem;
    top: 0.25rem;
    background: var(--primary);
    color: var(--white);
    font-size: 0.6rem;
    font-weight: 700;
    width: 18px;
    height: 18px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.comment-form-wrapper {
    margin: 0.5rem 0;
    padding: 1rem;
    background: var(--gray-50);
    border: 1px solid var(--border);
}

.paper-comments-panel {
    border-left: 1px solid var(--border);
    background: var(--bg);
    display: flex;
    flex-direction: column;
    position: sticky;
    top: var(--navbar-h);
    height: calc(100vh - var(--navbar-h));
    overflow-y: auto;
}

.comment-item { padding: 0.5rem 0; }

@media (max-width: 1200px) {
    .paper-layout { grid-template-columns: 200px 1fr; }
    .paper-comments-panel { display: none; }
}
@media (max-width: 768px) {
    .paper-layout { grid-template-columns: 1fr; }
    .paper-toc { position: static; height: auto; border-right: none; border-bottom: 1px solid var(--border); }
    .paper-content { height: auto; }
}