/* ==========================================================================
   components.css — header, hero, sections, cards, team, publications, footer
   ========================================================================== */

/* header / nav ------------------------------------------------------------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: saturate(180%) blur(10px);
    -webkit-backdrop-filter: saturate(180%) blur(10px);
    border-bottom: 1px solid var(--color-border);
}
.site-header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
}

.brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--color-text);
    letter-spacing: 0.01em;
}
.brand:hover { color: var(--color-accent); text-decoration: none; }
.brand-logo {
    width: 28px;
    height: 28px;
    border-radius: 6px;
    object-fit: contain;
    display: block;
}

.nav { display: flex; align-items: center; gap: 4px; }
.nav a {
    position: relative;
    color: var(--color-text);
    font-size: 0.92rem;
    font-weight: 500;
    padding: 8px 14px;
    border-radius: var(--radius-sm);
    transition: color 0.15s ease, background 0.15s ease;
}
.nav a:hover  { color: var(--color-accent); background: var(--color-accent-soft); text-decoration: none; }
.nav a.active { color: var(--color-accent); }
.nav a.active::after {
    content: "";
    position: absolute;
    left: 14px; right: 14px;
    bottom: -1px;
    height: 2px;
    background: var(--color-accent);
    border-radius: 2px;
}

.nav-toggle {
    display: none;
    background: transparent;
    border: 0;
    padding: 8px;
    cursor: pointer;
    color: var(--color-text);
}

@media (max-width: 760px) {
    .nav-toggle { display: inline-flex; }
    .nav {
        position: absolute;
        top: var(--header-height); left: 0; right: 0;
        flex-direction: column;
        align-items: stretch;
        background: #fff;
        border-bottom: 1px solid var(--color-border);
        padding: 8px;
        gap: 0;
        display: none;
    }
    .nav.open { display: flex; }
    .nav a { padding: 12px 16px; border-radius: 0; }
}

/* hero (home) -------------------------------------------------------------- */
.hero {
    padding: 72px 0 56px;
    background:
        radial-gradient(1200px 500px at 85% -10%, rgba(0, 48, 85, 0.06), transparent 60%),
        radial-gradient(900px 400px at 10% 10%,  rgba(0, 48, 85, 0.04), transparent 60%),
        var(--color-bg);
    border-bottom: 1px solid var(--color-border);
}
.hero-grid {
    display: grid;
    grid-template-columns: 1.3fr 1fr;
    gap: 56px;
    align-items: center;
}
.hero h1 { font-size: clamp(2.1rem, 4vw, 3rem); margin-bottom: 0.3em; }
.hero-lead {
    font-size: 1.08rem;
    color: var(--color-text-muted);
    max-width: 56ch;
    margin-bottom: 28px;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }

.hero-media {
    display: flex;
    justify-content: center;
    align-items: center;
}
.hero-media img {
    width: 180px; height: 180px;
    border-radius: var(--radius-lg);
    object-fit: contain;
    background: #fff;
    padding: 14px;
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
}

@media (max-width: 860px) {
    .hero-grid { grid-template-columns: 1fr; gap: 36px; }
    .hero-media img { width: 150px; height: 150px; }
    .hero { padding: 48px 0 36px; }
}

/* page header (non-home) --------------------------------------------------- */
.page-header {
    padding: 56px 0 28px;
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg-alt);
}
.page-header h1 { margin-bottom: 6px; }
.page-header p  { color: var(--color-text-muted); margin: 0; }

/* buttons ------------------------------------------------------------------ */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    border-radius: 999px;
    font-size: 0.92rem;
    font-weight: 500;
    border: 1px solid transparent;
    cursor: pointer;
    transition: all 0.15s ease;
    line-height: 1;
}
.btn-primary {
    background: var(--color-accent);
    color: #fff;
    border-color: var(--color-accent);
}
.btn-primary:hover {
    background: var(--color-accent-hi);
    border-color: var(--color-accent-hi);
    color: #fff;
    text-decoration: none;
}
.btn-ghost {
    background: #fff;
    color: var(--color-text);
    border-color: var(--color-border);
}
.btn-ghost:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
    text-decoration: none;
}

/* sections ----------------------------------------------------------------- */
.section       { padding: 72px 0; }
.section-alt   { background: var(--color-bg-alt); }
.section-tight { padding: 48px 0; }

.section-head { margin-bottom: 40px; }
.section-head h2 { margin: 0 0 6px; }
.section-head p  { color: var(--color-text-muted); max-width: 68ch; margin: 0; }

/* cards / grids ------------------------------------------------------------ */
.cards { display: grid; gap: 24px; }
.cards-2 { grid-template-columns: repeat(2, 1fr); }
.cards-3 { grid-template-columns: repeat(3, 1fr); }
.cards-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 960px) {
    .cards-4 { grid-template-columns: repeat(3, 1fr); }
    .cards-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
    .cards-4, .cards-3, .cards-2 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 420px) {
    .cards-4, .cards-3, .cards-2 { grid-template-columns: 1fr; }
}

.card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 22px;
    transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}
.card:hover { border-color: #d6dbe1; box-shadow: var(--shadow-sm); }
.card-title { font-size: 1.05rem; margin: 0 0 8px; }
.card-meta  { color: var(--color-text-muted); font-size: 0.88rem; margin: 0 0 10px; }
.card-body  { color: var(--color-text-muted); font-size: 0.95rem; }

/* research topics ---------------------------------------------------------- */
.topics {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}
@media (max-width: 820px) { .topics { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .topics { grid-template-columns: 1fr; } }

.topic {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 24px;
}
.topic .icon {
    width: 38px; height: 38px;
    border-radius: 10px;
    background: var(--color-accent-soft);
    color: var(--color-accent);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 14px;
}
.topic h3 { font-size: 1.05rem; margin: 0 0 6px; }
.topic p  { color: var(--color-text-muted); font-size: 0.94rem; margin: 0; }

/* stats -------------------------------------------------------------------- */
.stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
    padding: 32px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xs);
}
.stat     { text-align: center; padding: 12px; }
.stat .num {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--color-accent);
    font-variant-numeric: tabular-nums;
    line-height: 1.1;
}
.stat .lbl {
    color: var(--color-text-muted);
    font-size: 0.82rem;
    margin-top: 4px;
    letter-spacing: 0.02em;
}
@media (max-width: 640px) { .stats { grid-template-columns: repeat(2, 1fr); } }

/* team --------------------------------------------------------------------- */
.team-group { margin-bottom: 56px; }
.team-group h2 {
    font-size: 1.35rem;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--color-accent);
    display: inline-block;
    margin-bottom: 28px;
}

.team-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 28px 20px;
}
@media (max-width: 960px) { .team-grid { grid-template-columns: repeat(4, 1fr); } }
@media (max-width: 720px) { .team-grid { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 480px) { .team-grid { grid-template-columns: repeat(2, 1fr); } }

.person {
    text-align: center;
    max-width: 170px;
    margin: 0 auto;
}
.person .avatar {
    width: 140px;
    height: 140px;
    margin: 0 auto 12px;
    border-radius: 50%;
    background: var(--color-bg-alt);
    overflow: hidden;
    border: 1px solid var(--color-border);
    position: relative;
}
.person .avatar img {
    width: 100%; height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}
.person:hover .avatar img { transform: scale(1.04); }
.person .name {
    font-weight: 600;
    font-size: 0.95rem;
    margin: 0;
    line-height: 1.3;
}
.person .role {
    font-size: 0.82rem;
    color: var(--color-text-muted);
    margin: 2px 0 0;
}

/* alumni list -------------------------------------------------------------- */
.alumni-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px 28px;
    list-style: none;
    padding: 0;
    margin: 0;
}
@media (max-width: 640px) { .alumni-list { grid-template-columns: 1fr; } }

.alumni-list li {
    padding: 10px 0;
    border-bottom: 1px dashed var(--color-border);
    font-size: 0.94rem;
}
.alumni-list li .alum-name { font-weight: 600; }
.alumni-list li .alum-meta {
    color: var(--color-text-muted);
    display: block;
    font-size: 0.86rem;
    margin-top: 2px;
}

/* publications ------------------------------------------------------------- */
.pub-filter {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin: 0 0 28px;
    padding: 12px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    position: sticky;
    top: calc(var(--header-height) + 8px);
    z-index: 10;
    box-shadow: var(--shadow-xs);
}
.pub-filter button {
    background: transparent;
    border: 1px solid transparent;
    color: var(--color-text);
    padding: 6px 12px;
    border-radius: 999px;
    font-size: 0.84rem;
    cursor: pointer;
    transition: all 0.15s ease;
    font-weight: 500;
}
.pub-filter button:hover  { background: var(--color-accent-soft); color: var(--color-accent); }
.pub-filter button.active { background: var(--color-accent); color: #fff; }

.pub-section-title {
    margin-top: 60px;
    font-size: 1.6rem;
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 10px;
}

.year-block { margin-bottom: 40px; }
.year-block h2 {
    font-size: 1.35rem;
    margin-bottom: 16px;
    padding-bottom: 8px;
    border-bottom: 2px solid var(--color-accent);
    display: inline-block;
}

.pub-list {
    list-style: none;
    padding: 0;
    margin: 0;
    counter-reset: pub;
}
.pub-list li {
    padding: 14px 0 14px 44px;
    border-bottom: 1px solid var(--color-border-soft);
    font-size: 0.95rem;
    position: relative;
    counter-increment: pub;
}
.pub-list li::before {
    content: "[" counter(pub) "]";
    position: absolute;
    left: 0;
    top: 14px;
    color: var(--color-text-soft);
    font-variant-numeric: tabular-nums;
    font-size: 0.85rem;
    font-family: var(--font-mono);
}
.pub-list li:last-child { border-bottom: 0; }

.venue {
    display: inline-block;
    padding: 1px 8px;
    background: var(--color-accent-soft);
    color: var(--color-accent);
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-right: 6px;
    letter-spacing: 0.02em;
}

/* news list ---------------------------------------------------------------- */
.news-list { list-style: none; padding: 0; margin: 0; }
.news-list li {
    display: grid;
    grid-template-columns: 140px 1fr;
    gap: 16px;
    padding: 14px 0;
    border-bottom: 1px solid var(--color-border-soft);
    font-size: 0.95rem;
    align-items: baseline;
}
.news-list li:last-child { border-bottom: 0; }
.news-list .date {
    color: var(--color-text-soft);
    font-family: var(--font-mono);
    font-size: 0.82rem;
    white-space: nowrap;
}
@media (max-width: 560px) {
    .news-list li { grid-template-columns: 1fr; gap: 4px; }
}

/* projects (Our Work) ------------------------------------------------------ */
.projects {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
}
@media (max-width: 760px) { .projects { grid-template-columns: 1fr; } }

.project {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.project:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: #d6dbe1;
}
.project .thumb {
    height: 160px;
    background: var(--color-bg-alt);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}
.project .thumb img {
    max-width: 70%;
    max-height: 120px;
    width: auto;
    height: auto;
    object-fit: contain;
}
.project .body { padding: 24px; flex: 1; display: flex; flex-direction: column; }
.project h3    { margin: 0 0 8px; font-size: 1.25rem; }
.project p     { color: var(--color-text-muted); font-size: 0.95rem; margin: 0 0 16px; }
.project .project-link {
    margin-top: auto;
    align-self: flex-start;
    font-weight: 500;
    font-size: 0.92rem;
}
.project .project-link::after {
    content: " →";
    display: inline-block;
    transition: margin-left 0.15s ease;
}
.project .project-link:hover::after { margin-left: 3px; }

/* teaching ----------------------------------------------------------------- */
.course-card {
    display: grid;
    grid-template-columns: 240px 1fr;
    gap: 32px;
    padding: 28px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    margin-bottom: 40px;
    align-items: start;
}
.course-card img {
    width: 100%;
    max-width: 240px;
    border-radius: var(--radius);
    border: 1px solid var(--color-border);
}
@media (max-width: 760px) {
    .course-card { grid-template-columns: 1fr; padding: 22px; }
    .course-card img { max-width: 200px; }
}

.update-list { list-style: none; padding: 0; margin: 0; }
.update-list li {
    padding: 10px 14px;
    background: var(--color-bg-alt);
    border-left: 3px solid var(--color-accent);
    margin-bottom: 8px;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    font-size: 0.93rem;
}

/* photo carousel ----------------------------------------------------------- */
.carousel {
    position: relative;
    width: 100%;
    border-radius: var(--radius-lg);
    overflow: hidden;
    background: #f0f2f4;
    box-shadow: var(--shadow-md);
}
.carousel-track {
    display: flex;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}
.carousel-slide {
    flex: 0 0 100%;
    min-width: 0;
}
.carousel-slide img {
    width: 100%;
    height: auto;
    display: block;
}
.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(255,255,255,0.15);
    border: 1px solid rgba(255,255,255,0.3);
    color: #fff;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    backdrop-filter: blur(4px);
    transition: background 0.2s ease;
    z-index: 5;
    padding: 0;
    font-size: 18px;
    line-height: 1;
}
.carousel-btn:hover { background: rgba(255,255,255,0.3); }
.carousel-btn.prev { left: 14px; }
.carousel-btn.next { right: 14px; }
.carousel-dots {
    position: absolute;
    bottom: 12px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 7px;
    z-index: 5;
}
.carousel-dot {
    width: 8px; height: 8px;
    border-radius: 50%;
    background: rgba(255,255,255,0.5);
    border: none;
    cursor: pointer;
    padding: 0;
    transition: background 0.2s ease, transform 0.2s ease;
}
.carousel-dot.active {
    background: #fff;
    transform: scale(1.25);
}

/* footer ------------------------------------------------------------------- */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding: 36px 0 28px;
    color: var(--color-text-muted);
    font-size: 0.88rem;
    background: var(--color-bg-alt);
    margin-top: 80px;
}
.footer-grid {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 24px;
    align-items: center;
}
@media (max-width: 640px) {
    .footer-grid { grid-template-columns: 1fr; text-align: center; }
}

.social {
    display: flex;
    gap: 12px;
    align-items: center;
}
.social a {
    display: inline-flex;
    width: 34px; height: 34px;
    border-radius: 50%;
    background: #fff;
    border: 1px solid var(--color-border);
    align-items: center;
    justify-content: center;
    color: var(--color-text-muted);
    transition: all 0.15s ease;
}
.social a:hover {
    color: var(--color-accent);
    border-color: var(--color-accent);
    text-decoration: none;
}

.footer-legal {
    text-align: center;
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px dashed var(--color-border);
    font-size: 0.82rem;
}

/* ==========================================================================
   Responsive — tablet & mobile
   ========================================================================== */

@media (max-width: 760px) {
    .section       { padding: 48px 0; }
    .section-tight { padding: 32px 0; }
    .section-head  { margin-bottom: 28px; }

    /* carousel: bigger touch targets */
    .carousel-btn {
        width: 36px; height: 36px;
        font-size: 20px;
    }
    .carousel-btn.prev { left: 10px; }
    .carousel-btn.next { right: 10px; }
    .carousel-dot { width: 9px; height: 9px; }
}

@media (max-width: 520px) {
    :root {
        --container-padding: 16px;
        --header-height: 56px;
    }
    .section       { padding: 36px 0; }
    .section-head  { margin-bottom: 20px; }
    .hero          { padding: 36px 0 28px; }
    .hero-lead     { font-size: 1rem; }
    .hero-actions  { gap: 8px; }

    /* stats: 2 columns, tighter */
    .stats {
        padding: 20px 12px;
        gap: 4px;
    }
    .stat .num { font-size: 1.5rem; }

    /* news: hide date column on very small screens */
    .news-list li {
        grid-template-columns: 1fr;
        gap: 2px;
    }

    /* carousel: thinner arrow buttons on very small screens */
    .carousel-btn {
        width: 30px; height: 30px;
        font-size: 17px;
    }
    .carousel-btn.prev { left: 6px; }
    .carousel-btn.next { right: 6px; }

    /* footer */
    .site-footer { margin-top: 48px; padding: 28px 0 20px; }
}