/* ============================================================
   STDLAW Academic Website — Formal Academic Stylesheet
   Strict academic design language. No gradients, no glass,
   no animations, no decorative elements. Pure content focus.
   ============================================================ */

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

:root {
    --color-bg: #ffffff;
    --color-bg-alt: #f7f8fa;
    --color-text: #2c2c2c;
    --color-text-secondary: #555555;
    --color-text-muted: #777777;
    --color-primary: #1a2332;
    --color-primary-light: #2d3a4d;
    --color-accent: #8b0000;
    --color-border: #d0d0d0;
    --color-border-light: #e5e5e5;
    --color-link: #1a3c6e;
    --color-link-hover: #8b0000;

    --font-serif: Georgia, "Times New Roman", "Noto Serif SC", "Source Han Serif SC", serif;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    --font-mono: "Courier New", Consolas, monospace;

    --content-max: 1140px;
    --content-narrow: 820px;
}

html {
    font-size: 17.5px;
}

body {
    font-family: var(--font-serif);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
}

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

a:hover {
    color: var(--color-link-hover);
    text-decoration: underline;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* ---------- Top Institutional Bar ---------- */
.institution-bar {
    background: var(--color-primary);
    color: rgba(255, 255, 255, 0.85);
    font-size: 0.85rem;
    letter-spacing: 0.04em;
    padding: 7px 0;
    text-align: center;
}

.institution-bar a {
    color: rgba(255, 255, 255, 0.85);
}

.institution-bar a:hover {
    color: #ffffff;
    text-decoration: none;
}

/* ---------- Site Header ---------- */
.site-header {
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg);
    padding: 0;
}

.header-top {
    max-width: var(--content-max);
    margin: 0 auto;
    padding: 24px 20px 0;
    display: flex;
    align-items: center;
    gap: 16px;
}

.header-logo {
    height: 48px;
    width: auto;
    flex-shrink: 0;
}

.header-brand {
    display: flex;
    flex-direction: column;
}

.header-brand-title {
    font-family: var(--font-serif);
    font-size: 1.65rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1.2;
    letter-spacing: 0.02em;
}

.header-brand-sub {
    font-size: 0.88rem;
    color: var(--color-text-muted);
    letter-spacing: 0.03em;
    margin-top: 2px;
}

/* ---------- Navigation ---------- */
.main-nav {
    max-width: var(--content-max);
    margin: 0 auto;
    padding: 0 20px;
}

.nav-list {
    list-style: none;
    display: flex;
    gap: 0;
    border-top: 1px solid var(--color-border-light);
}

.nav-list li {
    margin: 0;
}

.nav-list a {
    display: block;
    padding: 12px 20px;
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    letter-spacing: 0.02em;
    border-bottom: 2px solid transparent;
}

.nav-list a:hover,
.nav-list a.active {
    color: var(--color-primary);
    text-decoration: none;
    border-bottom-color: var(--color-accent);
}

/* Mobile nav toggle */
.nav-toggle {
    display: none;
    background: none;
    border: 1px solid var(--color-border);
    padding: 6px 12px;
    cursor: pointer;
    font-size: 0.85rem;
    color: var(--color-text-secondary);
    font-family: var(--font-serif);
    margin-left: auto;
}

/* ---------- Page Title Area ---------- */
.page-title-area {
    background: var(--color-bg-alt);
    border-bottom: 1px solid var(--color-border-light);
    padding: 36px 20px 32px;
}

.page-title-inner {
    max-width: var(--content-max);
    margin: 0 auto;
}

.page-title-area h1 {
    font-family: var(--font-serif);
    font-size: 1.85rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1.3;
    margin-bottom: 8px;
}

.page-title-area p {
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    max-width: 680px;
    line-height: 1.7;
}

/* ---------- Main Content Area ---------- */
.content {
    max-width: var(--content-max);
    margin: 0 auto;
    padding: 40px 20px 60px;
}

.content-narrow {
    max-width: var(--content-narrow);
}

/* ---------- Section ---------- */
.section {
    margin-bottom: 48px;
}

.section:last-child {
    margin-bottom: 0;
}

.section-title {
    font-family: var(--font-serif);
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--color-primary);
    padding-bottom: 10px;
    border-bottom: 2px solid var(--color-primary);
    margin-bottom: 20px;
    line-height: 1.4;
}

.section-title-sm {
    font-family: var(--font-serif);
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: 12px;
}

.section-body p {
    margin-bottom: 16px;
    line-height: 1.8;
}

.section-body p:last-child {
    margin-bottom: 0;
}

/* ---------- Hero (Homepage) ---------- */
.hero-section {
    padding: 48px 20px 40px;
    max-width: var(--content-max);
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: 48px;
}

.hero-text {
    flex: 1;
}

.hero-text h1 {
    font-family: var(--font-serif);
    font-size: 2.2rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1.3;
    margin-bottom: 16px;
}

.hero-text .hero-tagline {
    font-size: 1.1rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: 20px;
    border-left: 3px solid var(--color-accent);
    padding-left: 16px;
}

.hero-logo {
    width: 220px;
    flex-shrink: 0;
}

/* ---------- Research Areas Grid ---------- */
.research-areas {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
    margin-top: 20px;
}

.research-area-item {
    padding: 24px;
    border: 1px solid var(--color-border-light);
    background: var(--color-bg);
}

.research-area-item h3 {
    font-family: var(--font-serif);
    font-size: 1.1rem;
    color: var(--color-primary);
    margin-bottom: 10px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--color-border-light);
    display: flex;
    align-items: center;
    gap: 8px;
}

.research-area-item h3 .area-icon {
    flex-shrink: 0;
    color: var(--color-primary);
}

.research-area-item p {
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    line-height: 1.75;
}

/* ---------- Research Direction Section (Research Page) ---------- */
.direction-section {
    margin-bottom: 40px;
    padding-bottom: 32px;
    border-bottom: 1px solid var(--color-border-light);
}

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

.direction-section h2 {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    color: var(--color-primary);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.direction-section h2 .direction-icon {
    flex-shrink: 0;
    color: var(--color-primary);
}

.direction-section p {
    font-size: 1rem;
    color: var(--color-text);
    line-height: 1.85;
}

/* Research overview table */
.research-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 24px;
    font-size: 0.95rem;
}

.research-table th,
.research-table td {
    padding: 10px 14px;
    text-align: left;
    border-bottom: 1px solid var(--color-border-light);
}

.research-table th {
    font-family: var(--font-serif);
    font-weight: 700;
    color: var(--color-primary);
    background: var(--color-bg-alt);
    border-bottom: 2px solid var(--color-border);
}

.research-table td {
    color: var(--color-text-secondary);
    line-height: 1.6;
}

/* ---------- About Page: Discipline Table ---------- */
.discipline-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 16px;
}

.discipline-table th,
.discipline-table td {
    padding: 14px 16px;
    text-align: left;
    vertical-align: top;
    border-bottom: 1px solid var(--color-border-light);
}

.discipline-table th {
    font-family: var(--font-serif);
    font-weight: 700;
    color: var(--color-primary);
    width: 160px;
    background: var(--color-bg-alt);
    border-right: 1px solid var(--color-border-light);
}

.discipline-table td {
    color: var(--color-text);
    line-height: 1.75;
}

.discipline-table th .disc-icon {
    display: inline-block;
    vertical-align: middle;
    margin-right: 4px;
    color: var(--color-primary);
}

/* Research highlights list (about page) */
.method-list {
    list-style: none;
    margin-top: 12px;
}

.method-list li {
    padding: 8px 0;
    border-bottom: 1px solid var(--color-border-light);
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.95rem;
    color: var(--color-text);
    line-height: 1.75;
}

.method-list li .list-icon {
    flex-shrink: 0;
    margin-top: 3px;
    color: var(--color-primary);
}

/* ---------- Project Layout ---------- */
.project-section {
    margin-bottom: 48px;
    padding-bottom: 40px;
    border-bottom: 1px solid var(--color-border-light);
}

.project-section:last-child {
    border-bottom: none;
    margin-bottom: 0;
}

.project-layout {
    display: flex;
    gap: 36px;
    align-items: flex-start;
}

.project-image {
    width: 200px;
    flex-shrink: 0;
}

.project-image img {
    border: 1px solid var(--color-border-light);
}

.project-domain-badge {
    display: inline-block;
    margin-top: 10px;
    font-size: 0.8rem;
    color: var(--color-text-muted);
    font-family: var(--font-mono);
}

.project-info h2 {
    font-family: var(--font-serif);
    font-size: 1.4rem;
    color: var(--color-primary);
    margin-bottom: 4px;
}

.project-info .project-en-name {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    margin-bottom: 12px;
    font-style: italic;
}

.project-info p {
    font-size: 1rem;
    color: var(--color-text);
    line-height: 1.8;
    margin-bottom: 12px;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 16px;
}

.project-tag {
    display: inline-block;
    font-size: 0.82rem;
    color: var(--color-text-secondary);
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border-light);
    padding: 3px 12px;
    letter-spacing: 0.02em;
}

.project-link {
    font-size: 0.95rem;
    font-weight: 600;
}

/* ---------- Team Page ---------- */

/* Leader */
.leader-section {
    display: flex;
    gap: 36px;
    align-items: flex-start;
    margin-bottom: 44px;
}

.leader-photo {
    width: 200px;
    flex-shrink: 0;
}

.leader-photo img {
    border: 1px solid var(--color-border-light);
}

.leader-info h2 {
    font-family: var(--font-serif);
    font-size: 1.4rem;
    color: var(--color-primary);
    margin-bottom: 6px;
}

.leader-info .member-role {
    display: block;
    font-size: 0.9rem;
    color: var(--color-accent);
    margin-bottom: 14px;
    font-weight: 600;
}

.leader-info .member-bio {
    font-size: 0.98rem;
    color: var(--color-text);
    line-height: 1.85;
}

/* Member grid */
.member-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 28px;
}

.member-card {
    text-align: center;
}

.member-card .member-photo {
    width: 100%;
    aspect-ratio: 1;
    overflow: hidden;
    margin-bottom: 12px;
    border: 1px solid var(--color-border-light);
}

.member-card .member-photo img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.member-card h3 {
    font-family: var(--font-serif);
    font-size: 1.05rem;
    color: var(--color-primary);
    margin-bottom: 2px;
}

.member-card .member-role {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    display: block;
    margin-bottom: 4px;
}

.member-card .member-link {
    font-size: 0.85rem;
}

/* ---------- Achievements ---------- */

/* Stats summary */
.stats-row {
    display: flex;
    gap: 0;
    border: 1px solid var(--color-border);
    margin-bottom: 40px;
}

.stat-item {
    flex: 1;
    text-align: center;
    padding: 24px 18px;
    border-right: 1px solid var(--color-border-light);
}

.stat-item:last-child {
    border-right: none;
}

.stat-number {
    font-family: var(--font-serif);
    font-size: 2.2rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1;
    margin-bottom: 8px;
}

.stat-label {
    font-size: 0.88rem;
    color: var(--color-text-muted);
    letter-spacing: 0.03em;
}

/* Paper/achievement lists */
.achievement-section {
    margin-bottom: 40px;
}

.achievement-section h2 {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    color: var(--color-primary);
    padding-bottom: 8px;
    border-bottom: 2px solid var(--color-primary);
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.achievement-section h2 .ach-icon {
    flex-shrink: 0;
    color: var(--color-primary);
}

/* Featured International Paper Card */
.paper-card {
    display: block;
    border: 2px solid var(--color-primary);
    border-radius: 6px;
    padding: 24px 28px;
    margin-bottom: 24px;
    background: var(--color-bg-alt);
}

.paper-card-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.paper-card-type {
    font-size: 0.88rem;
    color: var(--color-text-muted);
    font-weight: 500;
    letter-spacing: 0.02em;
}

.paper-card-badges {
    display: flex;
    gap: 8px;
}

.paper-badge {
    display: inline-block;
    font-size: 0.78rem;
    font-weight: 700;
    color: var(--color-bg);
    background: var(--color-primary);
    padding: 3px 10px;
    border-radius: 3px;
    letter-spacing: 0.05em;
}

.paper-card-title {
    font-family: var(--font-serif);
    font-size: 1.2rem;
    color: var(--color-primary);
    line-height: 1.5;
    margin-bottom: 12px;
    font-weight: 600;
}

.paper-card-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
    font-size: 0.92rem;
    color: var(--color-text-secondary);
}

.paper-card-authors {
    font-weight: 500;
}

.paper-card-divider {
    width: 1px;
    height: 16px;
    background: var(--color-border);
}

.paper-card-venue {
    font-style: italic;
    color: var(--color-text-muted);
}

.paper-card-footer {
    margin-top: 16px;
    padding-top: 14px;
    border-top: 1px solid var(--color-border);
}

.paper-card-footer-link {
    display: inline-block;
    font-size: 0.85rem;
    color: var(--color-primary);
    font-weight: 500;
    text-decoration: none;
    padding-bottom: 1px;
    border-bottom: 1px dashed var(--color-primary);
    transition: opacity 0.2s ease;
}

.paper-card-footer-link:hover {
    opacity: 0.7;
}

/* Featured achievement (e.g. adopted policy report) */
.achievement-featured {
    border: 2px solid var(--color-accent);
    padding: 24px 28px;
    margin-bottom: 32px;
    background: var(--color-bg-alt);
}

.achievement-featured .featured-label {
    display: inline-block;
    font-size: 0.78rem;
    color: var(--color-bg);
    background: var(--color-accent);
    padding: 2px 10px;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    margin-bottom: 12px;
    font-weight: 700;
}

.achievement-featured .featured-title {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    color: var(--color-primary);
    margin-bottom: 8px;
    line-height: 1.5;
}

.achievement-featured .featured-desc {
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
}

.achievement-list {
    list-style: none;
    counter-reset: ach-counter;
}

.achievement-list li {
    counter-increment: ach-counter;
    padding: 10px 0;
    border-bottom: 1px solid var(--color-border-light);
    display: flex;
    align-items: baseline;
    gap: 12px;
    font-size: 0.92rem;
    line-height: 1.7;
}

.achievement-list li::before {
    content: counter(ach-counter) ".";
    font-family: var(--font-serif);
    font-weight: 700;
    color: var(--color-primary);
    flex-shrink: 0;
    min-width: 24px;
}

.achievement-paper {
    flex: 1;
    color: var(--color-text);
}

.achievement-venue {
    display: block;
    color: var(--color-text-muted);
    font-size: 0.85rem;
    font-style: italic;
    margin-top: 4px;
}

.achievement-author {
    flex-shrink: 0;
    color: var(--color-text-muted);
    font-size: 0.85rem;
    min-width: 60px;
    text-align: right;
}

.achievement-soft {
    flex: 1;
    color: var(--color-text);
}

.achievement-regno {
    flex-shrink: 0;
    color: var(--color-text-muted);
    font-size: 0.85rem;
    font-family: var(--font-mono);
}

/* Certifications */
.cert-section {
    margin-top: 40px;
}

.cert-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}

.cert-table th,
.cert-table td {
    padding: 10px 14px;
    text-align: left;
    border-bottom: 1px solid var(--color-border-light);
}

.cert-table th {
    font-family: var(--font-serif);
    font-weight: 700;
    color: var(--color-primary);
    background: var(--color-bg-alt);
    border-bottom: 2px solid var(--color-border);
}

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

.cert-table .cert-code {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--color-text-muted);
}

/* ---------- Highlights (Homepage) ---------- */
.highlights {
    margin-top: 12px;
}

.highlight-item {
    padding: 12px 0;
    border-bottom: 1px solid var(--color-border-light);
    display: flex;
    gap: 16px;
    align-items: baseline;
}

.highlight-item:last-child {
    border-bottom: none;
}

.highlight-category {
    font-size: 0.82rem;
    color: var(--color-bg);
    background: var(--color-primary);
    padding: 1px 8px;
    flex-shrink: 0;
    letter-spacing: 0.04em;
}

.highlight-text {
    font-size: 0.95rem;
    color: var(--color-text);
    line-height: 1.7;
}

/* ---------- Quick Links (Homepage) ---------- */
.quick-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-top: 16px;
}

.quick-link-item {
    padding: 24px;
    border: 1px solid var(--color-border-light);
    background: var(--color-bg-alt);
}

.quick-link-item h3 {
    font-family: var(--font-serif);
    font-size: 1.05rem;
    color: var(--color-primary);
    margin-bottom: 10px;
}

.quick-link-item p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 12px;
}

.quick-link-item a {
    font-size: 0.9rem;
    font-weight: 600;
}

/* ---------- Footer ---------- */
.site-footer {
    background: var(--color-primary);
    color: rgba(255, 255, 255, 0.75);
    padding: 40px 20px 28px;
    margin-top: 60px;
    font-size: 0.9rem;
}

.footer-inner {
    max-width: var(--content-max);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    gap: 40px;
}

.footer-brand {
    flex: 1;
}

.footer-brand img {
    height: 32px;
    width: auto;
    margin-bottom: 8px;
    opacity: 0.9;
    filter: brightness(0) invert(1);
}

.footer-brand p {
    font-size: 0.85rem;
    line-height: 1.7;
}

.footer-links {
    display: flex;
    gap: 48px;
}

.footer-col h4 {
    font-size: 0.88rem;
    color: rgba(255, 255, 255, 0.95);
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: 0.03em;
}

.footer-col a {
    display: block;
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.85rem;
    padding: 3px 0;
}

.footer-col a:hover {
    color: #ffffff;
    text-decoration: none;
}

.footer-bottom {
    max-width: var(--content-max);
    margin: 24px auto 0;
    padding-top: 16px;
    border-top: 1px solid rgba(255, 255, 255, 0.12);
    display: flex;
    justify-content: space-between;
    font-size: 0.82rem;
    color: rgba(255, 255, 255, 0.4);
    flex-wrap: wrap;
    gap: 8px;
}

.footer-bottom a {
    color: rgba(255, 255, 255, 0.4);
}

.footer-bottom a:hover {
    color: rgba(255, 255, 255, 0.7);
}

.footer-beian {
    display: flex;
    gap: 16px;
    align-items: center;
    flex-wrap: wrap;
}

.footer-beian a {
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.beian-icon {
    height: 14px;
    width: auto;
    display: inline-block;
}

/* ---------- Responsive ---------- */

/* Tablet */
@media (max-width: 768px) {
    .hero-section {
        flex-direction: column;
        gap: 24px;
        text-align: center;
        padding: 32px 20px;
    }

    .hero-logo {
        width: 160px;
        order: -1;
    }

    .hero-text .hero-tagline {
        border-left: none;
        padding-left: 0;
        border-top: 2px solid var(--color-accent);
        padding-top: 12px;
    }

    .research-areas {
        grid-template-columns: 1fr;
    }

    .project-layout {
        flex-direction: column;
    }

    .project-image {
        width: 160px;
    }

    .leader-section {
        flex-direction: column;
    }

    .leader-photo {
        width: 140px;
    }

    .member-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 16px;
    }

    .stats-row {
        flex-wrap: wrap;
    }

    .stat-item {
        flex: 1 1 50%;
        border-bottom: 1px solid var(--color-border-light);
    }

    .footer-inner {
        flex-direction: column;
        gap: 24px;
    }

    .footer-links {
        gap: 32px;
    }

    .footer-bottom {
        flex-direction: column;
        gap: 4px;
    }

    .quick-links {
        grid-template-columns: 1fr;
    }
}

/* Mobile */
@media (max-width: 540px) {
    html {
        font-size: 15px;
    }

    .header-top {
        padding: 16px 16px 0;
    }

    .header-logo {
        height: 38px;
    }

    .header-brand-title {
        font-size: 1.25rem;
    }

    /* Nav: show toggle, hide list */
    .nav-toggle {
        display: block;
    }

    .main-nav {
        padding: 0 16px;
    }

    .nav-list {
        display: none;
        flex-direction: column;
        border-top: 1px solid var(--color-border-light);
    }

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

    .nav-list a {
        padding: 10px 0;
        border-bottom: 1px solid var(--color-border-light);
        border-bottom-width: 1px;
    }

    .nav-list a:hover,
    .nav-list a.active {
        border-bottom-color: var(--color-border-light);
    }

    .page-title-area {
        padding: 24px 16px 20px;
    }

    .content {
        padding: 28px 16px 40px;
    }

    .hero-section {
        padding: 24px 16px;
    }

    .member-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }

    .achievement-list li {
        flex-direction: column;
        gap: 2px;
    }

    .achievement-author,
    .achievement-regno {
        text-align: left;
        padding-left: 36px;
    }

    .footer-links {
        flex-direction: column;
        gap: 20px;
    }
}