/* ── Variables ────────────────────────────────────────────────────────────── */
:root {
    --color-bg:          #ffffff;
    --color-bg-alt:      #f7f7f5;
    --color-border:      #e5e5e0;
    --color-text:        #111111;
    --color-text-sec:    #333333;
    --color-text-muted:  #555555;
    --color-accent:      #1a6fb5;
    --color-accent-dark: #155a96;
    --font-sans:         'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --navbar-h:          60px;
    --max-w:             780px;
    --radius:            6px;
    --transition:        180ms ease;
}

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

html {
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.75;
    color: var(--color-text);
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
}

/* ── Container ────────────────────────────────────────────────────────────── */
.container {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 0 2rem;
}

/* ── Typography ───────────────────────────────────────────────────────────── */
h1 {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: var(--color-text);
    margin-bottom: 0.25rem;
}

h2 {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 1.75rem;
    padding-bottom: 0.6rem;
    border-bottom: 2px solid var(--color-border);
    text-transform: uppercase;
    letter-spacing: 0.06em;
}

h3 {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 0.9rem;
    margin-top: 2rem;
}

h3:first-child {
    margin-top: 0;
}

h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-text);
}

p {
    margin-bottom: 1rem;
    color: var(--color-text-sec);
}

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

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

strong {
    font-weight: 600;
    color: var(--color-text);
}

/* ── Navbar ───────────────────────────────────────────────────────────────── */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: var(--color-bg);
    border-bottom: 1px solid transparent;
    transition: border-color var(--transition), box-shadow var(--transition);
}

.navbar.scrolled {
    border-bottom-color: var(--color-border);
    box-shadow: 0 1px 4px rgba(0,0,0,0.06);
}

.nav-container {
    max-width: calc(var(--max-w) + 4rem);
    margin: 0 auto;
    padding: 0 2rem;
    height: var(--navbar-h);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--color-text);
    letter-spacing: -0.01em;
    text-decoration: none;
}

.nav-logo:hover {
    color: var(--color-accent);
    text-decoration: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 0;
    align-items: center;
}

.nav-menu a {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--color-text-muted);
    padding: 0.4rem 0.75rem;
    border-radius: var(--radius);
    text-decoration: none;
    transition: color var(--transition), background var(--transition);
}

.nav-menu a:hover {
    color: var(--color-text);
    background: var(--color-bg-alt);
    text-decoration: none;
}

.nav-link.active {
    color: var(--color-accent) !important;
}

/* CV pill */
.nav-cv {
    background: var(--color-text) !important;
    color: var(--color-bg) !important;
    margin-left: 0.25rem;
    padding: 0.35rem 0.85rem !important;
    border-radius: 999px !important;
    font-size: 0.8rem !important;
    font-weight: 600 !important;
}

.nav-cv:hover {
    background: var(--color-accent) !important;
    color: #fff !important;
    text-decoration: none;
}

/* Hamburger */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 32px;
    height: 32px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 2px;
}

.nav-toggle span {
    display: block;
    width: 100%;
    height: 1.5px;
    background: var(--color-text);
    border-radius: 2px;
    transition: all var(--transition);
}

/* ── Tab Wrapper & Panels ─────────────────────────────────────────────────── */
.tab-wrapper {
    padding-top: var(--navbar-h);
    min-height: calc(100vh - var(--navbar-h) - 57px);
}

.tab-panel {
    display: none;
}

.tab-panel.active {
    display: block;
    animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to   { opacity: 1; transform: translateY(0); }
}

.section-content {
    padding: 4rem 0 5rem;
}

/* ── About ────────────────────────────────────────────────────────────────── */
.about-container {
    padding-top: 4rem;
    padding-bottom: 5rem;
}
.about-grid {
    display: grid;
    grid-template-columns: 190px 1fr;
    gap: 3.5rem;
    align-items: start;
}

.about-photo img {
    width: 100%;
    border-radius: var(--radius);
    display: block;
    aspect-ratio: 3/4;
    object-fit: cover;
    object-position: top;
    filter: grayscale(10%);
}

.about-title {
    font-size: 1rem;
    font-weight: 500;
    color: var(--color-text-sec);
    margin-bottom: 0.1rem;
}

.about-institution {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 1.25rem;
}


.about-interests {
    margin-top: 1.5rem;
    margin-bottom: 1.5rem;
    padding: 1rem 1.25rem;
    background: var(--color-bg-alt);
    border-left: 3px solid var(--color-accent);
    border-radius: 0 var(--radius) var(--radius) 0;
}

.about-interests h3 {
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.07em;
    color: var(--color-text-muted);
    margin-top: 0;
    margin-bottom: 0.3rem;
}

.about-interests p {
    font-size: 0.95rem;
    color: var(--color-text-sec);
    margin-bottom: 0;
    line-height: 1.7;
    text-align: justify;
}

.about-bio {
    font-size: 0.975rem;
    font-weight: 450;
    line-height: 1.8;
    margin-bottom: 1rem;
    text-align: justify;
}

.about-bio a {
    color: var(--color-accent);
}

/* Social icons */
.about-links {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.social-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 34px;
    height: 34px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    color: var(--color-text-muted);
    transition: all var(--transition);
    text-decoration: none;
}

.social-link:hover {
    color: var(--color-accent);
    border-color: var(--color-accent);
    background: rgba(44,95,138,0.06);
    text-decoration: none;
    transform: translateY(-1px);
}


/* ── Contact ──────────────────────────────────────────────────────────────── */
.contact-list {
    display: flex;
    flex-direction: column;
    gap: 1.75rem;
}

.contact-item h4 {
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-text-muted);
    margin-bottom: 0.3rem;
}

.contact-item p {
    color: var(--color-text-sec);
    font-size: 0.95rem;
    margin-bottom: 0.15rem;
    line-height: 1.6;
}

.contact-item p:last-child {
    margin-bottom: 0;
}


.social-link.text-link {
    width: auto;
    padding: 0 0.85rem;
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.icon {
    width: 17px;
    height: 17px;
}

/* ── Research ─────────────────────────────────────────────────────────────── */
.section-intro {
    font-size: 1rem;
    margin-bottom: 2.5rem;
    color: var(--color-text-sec);
}

.research-category {
    margin-bottom: 2.5rem;
}

.research-category:last-child {
    margin-bottom: 0;
}

.research-section-title {
    font-size: 1.2rem !important;
    font-weight: 700 !important;
    text-transform: none !important;
    letter-spacing: 0 !important;
    color: var(--color-text) !important;
    margin-bottom: 1.25rem !important;
    padding-top: 1.75rem !important;
    border-top: 1px solid var(--color-border) !important;
    margin-top: 0.5rem !important;
}

.research-section-first {
    padding-top: 0 !important;
    border-top: none !important;
    margin-top: 0 !important;
}

.paper {
    padding: 1.25rem 1.35rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    margin-bottom: 0.85rem;
    background: var(--color-bg);
    transition: background var(--transition), border-color var(--transition), box-shadow var(--transition);
}

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

.paper:hover {
    background: var(--color-bg-alt);
    border-color: #c8c0b0;
    box-shadow: 0 2px 8px rgba(0,0,0,0.07);
}

.paper h4 {
    font-size: 0.975rem;
    font-weight: 600;
    line-height: 1.5;
    margin-bottom: 0.25rem;
    color: var(--color-text);
}

.authors {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-bottom: 0.5rem;
}


.paper-award {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-accent);
    margin-bottom: 0.25rem;
}

.paper-venues {
    font-size: 0.825rem;
    color: var(--color-text-muted);
    font-style: italic;
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

.paper-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    margin-top: 0.5rem;
}

.paper-links a,
.abstract-toggle {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.65rem;
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: 999px;
    border: 1px solid var(--color-border);
    color: var(--color-text-muted);
    background: transparent;
    cursor: pointer;
    font-family: var(--font-sans);
    transition: all var(--transition);
    text-decoration: none;
}

.paper-links a:hover,
.abstract-toggle:hover,
.abstract-toggle.open {
    border-color: var(--color-accent);
    color: var(--color-accent);
    background: rgba(44,95,138,0.06);
    text-decoration: none;
}

.abstract-content {
    display: none;
    margin-top: 0.85rem;
    padding: 1rem 1.25rem;
    background: var(--color-bg-alt);
    border-left: 3px solid var(--color-accent);
    font-size: 0.9rem;
}

.abstract-content p {
    margin-bottom: 0;
    color: var(--color-text-sec);
    line-height: 1.75;
}

.abstract-content.open {
    display: block;
}

.wip-list {
    list-style: none;
    padding: 0;
}

.wip-list li {
    padding: 0.65rem 0 0.65rem 1.25rem;
    position: relative;
    color: var(--color-text-sec);
    font-size: 0.95rem;
    border-bottom: 1px solid var(--color-border);
}

.wip-list li:last-child {
    border-bottom: none;
}

.wip-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--color-accent);
}

.teaching-awards {
    list-style: none;
    padding: 0;
    margin-top: 0.5rem;
    grid-column: 1 / -1;
    border: none;
}

.teaching-awards li {
    border: none !important;
}

.teaching-awards li {
    font-size: 0.825rem;
    color: var(--color-accent);
    padding: 0;
    line-height: 1.4;
}

/* ── Teaching ─────────────────────────────────────────────────────────────── */
.teaching-block h3 {
    font-size: 1.1rem;
    font-weight: 700;
    text-transform: none;
    letter-spacing: 0;
    color: var(--color-text);
    margin-top: 0;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--color-border);
}

.teaching-block {
    margin-bottom: 2.5rem;
}

.teaching-block:last-child {
    margin-bottom: 0;
}

.teaching-sub {
    margin-bottom: 1.5rem;
}

.teaching-sub:last-child {
    margin-bottom: 0;
}

.teaching-level {
    font-size: 0.72rem !important;
    font-weight: 700 !important;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text-muted) !important;
    margin-bottom: 0.6rem !important;
    margin-top: 1rem !important;
}

.teaching-list {
    list-style: none;
    padding: 0;
}

.teaching-list li {
    display: grid;
    grid-template-columns: 1fr auto;
    grid-template-rows: auto auto;
    column-gap: 2rem;
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--color-border);
    align-items: start;
}

.teaching-list li:last-child {
    border-bottom: none;
}

.course-name {
    grid-column: 1;
    grid-row: 1;
    font-weight: 500;
    color: var(--color-text);
    font-size: 0.95rem;
}

.course-role {
    grid-column: 1;
    grid-row: 2;
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-top: 0.1rem;
}

.course-role em {
    font-style: normal;
    color: var(--color-accent);
}

.course-terms {
    grid-column: 2;
    grid-row: 1 / 3;
    font-size: 0.8rem;
    color: var(--color-text-muted);
    white-space: nowrap;
    text-align: right;
    padding-top: 0.1rem;
    font-style: italic;
}

/* ── Footer ───────────────────────────────────────────────────────────────── */
footer {
    padding: 1.25rem 0;
    border-top: 1px solid var(--color-border);
    background: var(--color-bg-alt);
}

.footer-inner {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    text-align: center;
}

.footer-contact {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
    font-size: 0.875rem;
}

.footer-sep {
    color: var(--color-text-muted);
}

.footer-copy {
    font-size: 0.78rem;
    color: var(--color-text-muted);
    margin-bottom: 0;
}

/* ── Responsive ───────────────────────────────────────────────────────────── */
@media (max-width: 680px) {
    html { font-size: 15px; }

    .container { padding: 0 1.25rem; }
    .nav-container { padding: 0 1.25rem; }

    .nav-menu {
        position: fixed;
        top: var(--navbar-h);
        left: 0;
        right: 0;
        background: var(--color-bg);
        flex-direction: column;
        padding: 0.75rem 1.25rem 1rem;
        gap: 0;
        border-bottom: 1px solid var(--color-border);
        box-shadow: 0 4px 12px rgba(0,0,0,0.08);
        transform: translateY(-110%);
        opacity: 0;
        visibility: hidden;
        transition: all 200ms ease;
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-menu li { width: 100%; }
    .nav-menu a  { display: block; padding: 0.65rem 0.5rem; }
    .nav-cv      { text-align: center; margin: 0.35rem 0 0; }
    .nav-toggle  { display: flex; }

    .nav-toggle.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
    .nav-toggle.active span:nth-child(2) { opacity: 0; }
    .nav-toggle.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

    .about-container { padding-top: 2.5rem; padding-bottom: 3.5rem; }
    .section-content { padding: 2.5rem 0 3.5rem; }

    h1 { font-size: 1.65rem; }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 1.75rem;
    }

    .about-photo {
        max-width: 140px;
    }

    .about-photo img { aspect-ratio: 3/4; }

    .teaching-list li {
        grid-template-columns: 1fr;
        grid-template-rows: auto auto auto;
    }

    .course-terms {
        grid-column: 1;
        grid-row: 3;
        text-align: left;
        margin-top: 0.2rem;
        white-space: normal;
    }
}

@media (max-width: 420px) {
    .container { padding: 0 1rem; }
}

/* ── Print ────────────────────────────────────────────────────────────────── */
@media print {
    .navbar { display: none !important; }
    .tab-wrapper { padding-top: 0; }
    .tab-panel { display: block; }
}