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

/* Design System Variables */
:root {
    --ink: #1a2332;
    --ink-light: #4a5568;
    --ink-muted: #718096;
    --accent: #3a8f8a;
    --accent-hover: #2b6e6a;
    --accent-bg: #eaf3f2;
    --bg: #faf9f7;
    --bg-white: #ffffff;
    --border: #e2e0dc;
    --border-light: #f0eee9;
    --header-bg: #2a3a4a;
    --footer-bg: #2a3a4a;
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.5rem;
    --space-6: 2rem;
    --space-7: 3rem;
    --space-8: 4rem;
}

/* Base Typography */
body {
    font-family: 'Source Sans 3', -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    font-size: 1rem;
    line-height: 1.75;
    color: var(--ink);
    background-color: var(--bg);
    overflow-x: hidden;
}

h1, h2, h3, h4 {
    font-family: 'Source Serif 4', Georgia, 'Times New Roman', serif;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: var(--space-4);
    color: var(--ink);
}

h5, h6 {
    font-family: 'Source Sans 3', sans-serif;
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: var(--space-3);
    color: var(--ink);
}

p {
    margin-bottom: 1.25rem;
    font-size: 1.05rem;
    color: var(--ink-light);
    line-height: 1.75;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color 0.15s;
}

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

/* Header & Navigation */
header {
    background-color: var(--header-bg);
    border-bottom: 1px solid rgba(255,255,255,0.08);
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1.5rem;
}

.site-name {
    font-family: 'Source Serif 4', serif;
    font-size: 1rem;
    font-weight: 600;
    color: rgba(255,255,255,0.92);
    text-decoration: none;
    white-space: nowrap;
    letter-spacing: 0.01em;
}

.site-name:hover {
    color: #ffffff;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 0.25rem;
    margin: 0;
    padding: 0;
    flex-wrap: wrap;
    justify-content: flex-end;
}

nav ul li a {
    color: rgba(255,255,255,0.65);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 400;
    padding: 0.4rem 0.75rem;
    border-radius: 4px;
    transition: color 0.15s, background-color 0.15s;
    display: block;
    white-space: nowrap;
}

nav ul li a:hover {
    color: #ffffff;
    background-color: rgba(255,255,255,0.1);
}

nav ul li a.active {
    color: #ffffff;
    background-color: var(--accent);
    font-weight: 500;
}

/* Main Content Container */
main {
    max-width: 780px;
    margin: var(--space-6) auto var(--space-8);
    background-color: var(--bg-white);
    padding: var(--space-6) var(--space-7);
    border: 1px solid var(--border-light);
}

main.homepage {
    max-width: 720px;
    padding: var(--space-7) var(--space-5);
    border: none;
    background: transparent;
}

main.page-wide {
    max-width: 960px;
}

/* Page Layout with Sticky TOC */
.page-layout {
    display: grid;
    grid-template-columns: 1fr minmax(0, 780px) 200px;
    gap: 0 var(--space-6);
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-6) var(--space-4);
}

.page-layout main {
    grid-column: 2;
    margin: 0;
    max-width: none;
}

.page-layout main.page-wide {
    max-width: none;
}

.page-toc {
    grid-column: 3;
    position: relative;
}

.toc-nav {
    position: sticky;
    top: 80px;
    max-height: calc(100vh - 100px);
    overflow-y: auto;
    font-size: 0.82rem;
    padding-top: var(--space-4);
}

.toc-nav h3 {
    font-family: 'Source Sans 3', sans-serif;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--ink-muted);
    margin-bottom: var(--space-3);
}

.toc-nav ul {
    list-style: none;
    padding-left: 0;
    border-left: 1px solid var(--border);
}

.toc-nav ul ul {
    padding-left: var(--space-3);
    border-left: none;
}

.toc-nav a {
    display: block;
    padding: 0.2rem 0 0.2rem var(--space-3);
    color: var(--ink-muted);
    text-decoration: none;
    line-height: 1.4;
    transition: color 0.15s;
}

.toc-nav a:hover,
.toc-nav a.active {
    color: var(--accent);
}

/* Page Header & Breadcrumb */
.page-header {
    margin-bottom: var(--space-6);
    padding-bottom: var(--space-4);
    border-bottom: 1px solid var(--border);
}

.page-header h2 {
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--ink);
    margin-bottom: 0.25rem;
}

.breadcrumb {
    font-size: 0.85rem;
    color: var(--ink-muted);
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

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

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

/* Homepage */
.hero {
    text-align: center;
    margin-bottom: var(--space-7);
}

.hero h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--ink);
    line-height: 1.3;
    margin-bottom: var(--space-3);
}

.hero .subtitle {
    font-size: 1.1rem;
    color: var(--ink-light);
    line-height: 1.6;
    margin-bottom: var(--space-3);
}

.hero .affiliation {
    font-size: 0.9rem;
    color: var(--ink-muted);
    font-style: italic;
}

.divider {
    border: none;
    border-top: 1px solid var(--border);
    margin: 0 0 var(--space-7);
}

.toc h2 {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--ink);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-bottom: var(--space-5);
}

.toc-list {
    list-style: none;
    counter-reset: toc-counter;
    padding: 0;
}

.toc-list li {
    counter-increment: toc-counter;
    margin-bottom: var(--space-2);
}

.toc-list li a {
    display: block;
    padding: var(--space-3) var(--space-4);
    text-decoration: none;
    border-radius: 4px;
    transition: background-color 0.15s;
    border-left: 3px solid transparent;
}

.toc-list li a:hover {
    background-color: var(--accent-bg);
    border-left-color: var(--accent);
}

.toc-list li a::before {
    content: counter(toc-counter) ". ";
    font-family: 'Source Serif 4', serif;
    font-weight: 600;
    color: var(--ink-muted);
}

.toc-title {
    font-weight: 600;
    color: var(--accent);
}

.toc-desc {
    font-size: 0.9rem;
    color: var(--ink-muted);
    display: block;
    margin-top: 2px;
    padding-left: 1.5rem;
}

/* Content Sections */
.content-section {
    margin-bottom: var(--space-7);
}

.content-section h3 {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: var(--space-4);
    padding-bottom: var(--space-2);
    border-bottom: 1px solid var(--border);
}

.content-section p {
    color: var(--ink-light);
    line-height: 1.75;
    text-align: justify;
    hyphens: auto;
}

/* Sub-sections */
.sub-section {
    margin-bottom: var(--space-7);
    padding-bottom: var(--space-5);
    border-bottom: 1px solid var(--border-light);
}

.sub-section:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.sub-section h4 {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: var(--space-4);
}

.sub-section h5,
.sample-type h5,
.qc-type h5 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: var(--space-3);
    margin-top: var(--space-5);
}

/* Tables */
.table-header {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    margin-top: var(--space-6);
    margin-bottom: var(--space-3);
    padding-bottom: var(--space-2);
    border-bottom: 1px solid var(--border);
}

.table-header h5 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--ink);
    margin: 0;
}

.download-btn {
    font-family: 'Source Sans 3', sans-serif;
    font-size: 0.8rem;
    color: var(--accent);
    background: none;
    border: 1px solid var(--accent);
    border-radius: 3px;
    padding: 0.3rem 0.75rem;
    cursor: pointer;
    transition: background-color 0.15s, color 0.15s;
    white-space: nowrap;
}

.download-btn:hover {
    background-color: var(--accent);
    color: #ffffff;
}

.download-btn i {
    margin-right: 0.3rem;
    font-size: 0.75rem;
}

.table-container {
    overflow-x: auto;
    margin-bottom: var(--space-6);
    border: 1px solid var(--border);
    border-radius: 3px;
}

table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
    line-height: 1.5;
}

table th {
    background-color: var(--bg);
    color: var(--ink);
    font-weight: 600;
    font-size: 0.82rem;
    padding: 0.6rem 0.75rem;
    border-bottom: 2px solid var(--border);
    text-align: left;
    position: sticky;
    top: 0;
    z-index: 2;
    white-space: nowrap;
}

table td {
    padding: 0.5rem 0.75rem;
    border-bottom: 1px solid var(--border-light);
    color: var(--ink-light);
    vertical-align: top;
}

table td:first-child {
    font-weight: 500;
    color: var(--ink);
    white-space: nowrap;
}

table tr:hover td {
    background-color: var(--accent-bg);
}

/* Downloads */
.downloads,
.download-category {
    margin-top: var(--space-4);
}

.download-category h6,
.downloads h6 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: var(--space-3);
}

.download-category ul,
.download-links ul,
.downloads ul {
    list-style: none;
    padding: 0;
}

.download-category li,
.download-links li,
.downloads li {
    margin-bottom: var(--space-2);
    padding: 0.4rem 0;
}

.download-category a,
.download-links a,
.downloads a {
    color: var(--accent);
    text-decoration: none;
    font-size: 0.95rem;
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    border-bottom: 1px solid transparent;
    transition: border-color 0.15s;
}

.download-category a:hover,
.download-links a:hover,
.downloads a:hover {
    border-bottom-color: var(--accent);
}

.download-category a i,
.download-links a i,
.download-links li i,
.downloads a i {
    font-size: 0.85rem;
    color: var(--accent);
}

/* Authors */
.author-grid {
    margin-bottom: var(--space-6);
}

.author-names {
    font-size: 1.1rem;
    line-height: 1.6;
    margin-bottom: var(--space-5);
    color: var(--ink);
}

.affiliation {
    padding: var(--space-3) 0;
    border-top: 1px solid var(--border-light);
}

.affiliation p {
    font-size: 0.95rem;
    color: var(--ink-muted);
    margin-bottom: var(--space-2);
}

.corresponding-author {
    margin-top: var(--space-6);
}

.corresponding-author h3 {
    font-size: 1.2rem;
    border-bottom: none;
    padding-bottom: 0;
}

.contact-info {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-4);
    margin-top: var(--space-4);
}

.contact-card {
    background-color: var(--bg);
    padding: var(--space-4);
    border: 1px solid var(--border);
    border-radius: 3px;
    flex: 1;
    min-width: 220px;
    transition: border-color 0.15s;
}

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

.contact-name {
    font-weight: 600;
    font-size: 1.05rem;
    color: var(--ink);
    margin-bottom: 0.3rem;
}

.contact-email {
    font-size: 0.9rem;
    color: var(--ink-muted);
    display: flex;
    align-items: center;
}

.contact-email i {
    margin-right: 0.4rem;
    color: var(--accent);
}

.institution-info {
    background-color: var(--bg);
    padding: var(--space-4);
    border: 1px solid var(--border);
    border-radius: 3px;
}

/* Introduction page */
.project-goals {
    list-style: none;
    margin: var(--space-4) 0;
    padding-left: 0;
}

.project-goals li {
    margin-bottom: var(--space-3);
    padding-left: var(--space-5);
    position: relative;
    color: var(--ink-light);
}

.project-goals li::before {
    content: "\2022";
    position: absolute;
    left: 0.5rem;
    color: var(--accent);
    font-weight: bold;
}

.reference-section {
    margin-top: var(--space-7);
}

.references {
    padding-left: var(--space-5);
    margin-top: var(--space-4);
}

.references li {
    margin-bottom: var(--space-3);
    color: var(--ink-muted);
    font-size: 0.95rem;
}

/* Workflow page */
.workflow-step {
    margin-bottom: var(--space-6);
    padding-bottom: var(--space-5);
    border-bottom: 1px solid var(--border-light);
}

.workflow-step:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.figure-placeholder {
    padding: var(--space-5);
    background-color: var(--bg);
    border: 1px solid var(--border);
    border-radius: 3px;
    text-align: center;
    margin: var(--space-5) 0;
}

.figure-placeholder p {
    color: var(--ink-muted);
    text-align: center;
    margin: 0;
}

/* Footer */
footer {
    background-color: var(--footer-bg);
    color: rgba(255,255,255,0.85);
    padding: var(--space-6) var(--space-5);
    margin-top: var(--space-8);
}

.footer-content {
    max-width: 780px;
    margin: 0 auto;
}

.footer-main {
    margin-bottom: var(--space-4);
    padding-bottom: var(--space-4);
    border-bottom: 1px solid rgba(255,255,255,0.15);
}

.footer-title {
    font-family: 'Source Serif 4', serif;
    font-size: 1rem;
    font-weight: 600;
    color: rgba(255,255,255,0.95);
    margin-bottom: var(--space-2);
}

.footer-institution {
    font-size: 0.85rem;
    color: rgba(255,255,255,0.65);
    margin: 0;
}

.footer-meta p {
    font-size: 0.82rem;
    color: rgba(255,255,255,0.6);
    margin-bottom: var(--space-2);
    line-height: 1.5;
}

.footer-meta a {
    color: rgba(255,255,255,0.8);
    text-decoration: underline;
    text-decoration-color: rgba(255,255,255,0.3);
}

.footer-meta a:hover {
    color: #ffffff;
}

.footer-update {
    font-size: 0.78rem;
    color: rgba(255,255,255,0.4);
    margin-top: var(--space-3);
}

/* Ask ChatBiobank floating link */
.ask-biomenthor {
    position: fixed;
    bottom: 24px;
    right: 24px;
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    background-color: var(--ink);
    color: rgba(255,255,255,0.9);
    text-decoration: none;
    border-radius: 24px;
    font-size: 0.85rem;
    font-weight: 500;
    transition: background-color 0.15s, transform 0.15s;
    z-index: 50;
    box-shadow: 0 2px 12px rgba(0,0,0,0.15);
}

.ask-biomenthor:hover {
    background-color: var(--accent);
    color: #fff;
    transform: translateY(-2px);
}

.ask-biomenthor i {
    font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 1100px) {
    .page-layout {
        display: block;
    }
    .page-toc {
        display: none;
    }
    .page-layout main {
        max-width: 780px;
        margin: var(--space-6) auto var(--space-8);
    }
}

@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: var(--space-2);
        padding: 0.5rem 1rem;
    }

    nav ul {
        justify-content: center;
    }

    main {
        padding: var(--space-4);
        margin: var(--space-4) var(--space-2);
    }

    main.homepage {
        padding: var(--space-5) var(--space-4);
    }

    .hero h1 {
        font-size: 1.5rem;
    }

    .contact-info {
        flex-direction: column;
    }

    .contact-card {
        min-width: auto;
    }

    .footer-content {
        padding: 0 var(--space-3);
    }

    .table-container {
        margin-left: calc(-1 * var(--space-4));
        margin-right: calc(-1 * var(--space-4));
        border-radius: 0;
        border-left: none;
        border-right: none;
    }
}