/* ═══════════════════════════════════════════════════════
   HONGBO LI — ACADEMIC HOMEPAGE
   Theme: Midnight Academic
   Fonts: Playfair Display (headings) + Source Sans 3 (body)
   ═══════════════════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:ital,wght@0,500;0,600;0,700;1,400&family=Source+Sans+3:ital,wght@0,300;0,400;0,600;1,400&display=swap');

:root {
    --navy:        #16213E;
    --navy-mid:    #1F2D52;
    --gold:        #C5802A;
    --gold-light:  rgba(197, 128, 42, 0.10);
    --cream:       #F8F7F4;
    --white:       #FFFFFF;
    --ink:         #111827;
    --text:        #374151;
    --muted:       #9CA3AF;
    --border:      #E5E7EB;
    --blue:        #1D4ED8;
    --blue-soft:   rgba(29, 78, 216, 0.08);
    --red:         #DC2626;
    --green:       #15803D;
    --amber:       #B45309;

    --sidebar-w:   306px;
    --nav-h:       72px;

    --font-h: 'Playfair Display', Georgia, 'Times New Roman', serif;
    --font-b: 'Source Sans 3', -apple-system, 'Helvetica Neue', sans-serif;
}

/* ── RESET ─────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 18px; }

body {
    font-family: var(--font-b);
    background: var(--cream);
    color: var(--text);
    line-height: 1.75;
    font-size: 20px;
    min-height: 100vh;
}

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(197,128,42,0.3); border-radius: 3px; }

/* ── SIDEBAR ────────────────────────────────────────────── */
.sidebar {
    width: var(--sidebar-w);
    min-width: var(--sidebar-w);
    background: var(--navy);
    position: sticky;
    top: var(--nav-h);
    height: calc(100vh - var(--nav-h));
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    padding: 55px 35px 45px;
    border-right: 2px solid var(--gold);
    z-index: 10;
}

.sidebar-photo {
    width: 224px;
    height: 224px;
    border-radius: 50%;
    object-fit: cover;
    display: block;
    margin: 0 auto 26px;
    border: 3px solid var(--gold);
    box-shadow: 0 0 0 9px rgba(197,128,42,0.14), 0 10px 34px rgba(0,0,0,0.35);
    transition: box-shadow 0.3s;
}

.sidebar-photo:hover {
    box-shadow: 0 0 0 14px rgba(197,128,42,0.2), 0 12px 42px rgba(0,0,0,0.4);
}

.sidebar-name {
    font-family: var(--font-h);
    font-size: 1.6rem;
    font-weight: 700;
    color: #fff;
    text-align: center;
    letter-spacing: 0.01em;
    margin-bottom: 6px;
}

.sidebar-role {
    font-size: 0.82rem;
    color: rgba(255,255,255,0.42);
    text-align: center;
    letter-spacing: 0.09em;
    text-transform: uppercase;
    font-weight: 300;
    line-height: 1.55;
    margin-bottom: 28px;
}

.sidebar-hr {
    border: none;
    border-top: 1px solid rgba(255,255,255,0.08);
    margin-bottom: 22px;
}

.sidebar-meta {
    list-style: none;
    margin-bottom: 20px;
}

.sidebar-meta li {
    display: flex;
    align-items: flex-start;
    gap: 11px;
    margin-bottom: 10px;
    font-size: 0.9rem;
    color: rgba(255,255,255,0.6);
    line-height: 1.45;
}

.sidebar-meta li i {
    color: var(--gold);
    font-size: 0.77rem;
    min-width: 14px;
    text-align: center;
    margin-top: 2px;
    flex-shrink: 0;
}

.sidebar-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 3px;
    margin-top: auto;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.08);
}

.sidebar-links a {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.9rem;
    color: rgba(255,255,255,0.52);
    text-decoration: none;
    padding: 7px 10px;
    border-radius: 7px;
    letter-spacing: 0.03em;
    transition: all 0.2s;
}

.sidebar-links a i {
    font-size: 0.95rem;
    min-width: 16px;
    text-align: center;
}

.sidebar-links a:hover {
    background: rgba(197,128,42,0.13);
    color: var(--gold);
    transform: translateX(3px);
}

/* ── PAGE WRAPPER (centered container) ──────────────────── */
.page-wrapper {
    max-width: 1500px;
    margin: 0 auto;
    display: flex;
    align-items: flex-start;
    padding-top: var(--nav-h);
    min-height: 100vh;
}

/* ── TOP NAV ────────────────────────────────────────────── */
.topnav {
    position: fixed;
    top: 0; left: 0; right: 0;
    height: var(--nav-h);
    background: rgba(248, 247, 244, 0.93);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 60px;
    gap: 2px;
    z-index: 190;
}

.topnav a {
    font-family: var(--font-b);
    font-size: 1rem;
    font-weight: 600;
    color: var(--text);
    text-decoration: none;
    padding: 8px 18px;
    border-radius: 6px;
    letter-spacing: 0.04em;
    transition: all 0.2s;
}

.topnav a:hover,
.topnav a.active {
    color: var(--gold);
    background: var(--gold-light);
}

/* ── MAIN ───────────────────────────────────────────────── */
.main {
    flex: 1;
    min-height: calc(100vh - var(--nav-h));
}

.content {
    max-width: 1080px;
    padding: 68px 72px 115px;
    margin: 0 auto;
}

/* ── PAGE TITLE ─────────────────────────────────────────── */
.page-title {
    margin-bottom: 50px;
}

.page-title h1 {
    font-family: var(--font-h);
    font-size: 3.2rem;
    font-weight: 700;
    color: var(--ink);
    line-height: 1.13;
    letter-spacing: -0.01em;
}

.page-title .tagline {
    margin-top: 8px;
    font-size: 1rem;
    color: var(--muted);
    letter-spacing: 0.07em;
    text-transform: uppercase;
    font-weight: 300;
}

/* ── SECTIONS ───────────────────────────────────────────── */
.section {
    margin-bottom: 62px;
    opacity: 0;
    animation: rise 0.55s ease forwards;
}

.section:nth-child(1) { animation-delay: 0.06s; }
.section:nth-child(2) { animation-delay: 0.13s; }
.section:nth-child(3) { animation-delay: 0.20s; }
.section:nth-child(4) { animation-delay: 0.27s; }
.section:nth-child(5) { animation-delay: 0.34s; }
.section:nth-child(6) { animation-delay: 0.41s; }

@keyframes rise {
    from { opacity: 0; transform: translateY(16px); }
    to   { opacity: 1; transform: translateY(0); }
}

.section h2 {
    font-family: var(--font-h);
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border);
    position: relative;
}

.section h2::after {
    content: '';
    position: absolute;
    bottom: -1px; left: 0;
    width: 38px; height: 2px;
    background: var(--gold);
}

/* ── ABOUT ──────────────────────────────────────────────── */
.about-p {
    font-size: 1.1rem;
    line-height: 1.88;
    color: var(--text);
}

.about-p a {
    color: var(--blue);
    text-decoration: none;
    border-bottom: 1px solid rgba(29,78,216,0.25);
    transition: border-color 0.2s;
}

.about-p a:hover { border-color: var(--blue); }

/* ── RESEARCH TAGS ──────────────────────────────────────── */
.research-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.rtag {
    display: inline-flex;
    align-items: center;
    gap: 9px;
    background: var(--white);
    border: 1px solid var(--border);
    padding: 11px 25px;
    border-radius: 100px;
    font-size: 1rem;
    color: var(--ink);
    transition: all 0.2s;
    cursor: default;
}

.rtag .dot {
    width: 6px; height: 6px;
    border-radius: 50%;
    background: var(--gold);
    flex-shrink: 0;
}

.rtag:hover {
    border-color: var(--gold);
    background: var(--gold-light);
}

/* ── NEWS ───────────────────────────────────────────────── */
.news-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 13px;
}

.news-item {
    display: flex;
    gap: 12px;
    align-items: flex-start;
}

.news-tag {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--blue);
    letter-spacing: 0.05em;
    text-transform: uppercase;
    background: var(--blue-soft);
    padding: 2px 7px;
    border-radius: 4px;
    white-space: nowrap;
    margin-top: 2px;
    flex-shrink: 0;
}

.news-body {
    font-size: 1.05rem;
    line-height: 1.65;
    flex: 1;
}

.hl-red { color: var(--red); font-weight: 700; }

/* ── AWARDS ─────────────────────────────────────────────── */
.awards-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.awards-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 16px 22px;
    background: var(--white);
    border-radius: 6px;
    border-left: 3px solid var(--gold);
    font-size: 1.05rem;
    line-height: 1.5;
}

.awards-list li::before {
    content: '★';
    color: var(--gold);
    font-size: 0.72rem;
    margin-top: 3px;
    flex-shrink: 0;
}

/* ── CONTACT ────────────────────────────────────────────── */
.contact-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.contact-list li {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.05rem;
}

.contact-list li i {
    color: var(--gold);
    min-width: 18px;
    text-align: center;
}

/* ── PUBLICATIONS ───────────────────────────────────────── */
.pub-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.pub-card {
    background: var(--white);
    border-radius: 8px;
    border: 1px solid var(--border);
    border-left: 3px solid transparent;
    padding: 25px 30px;
    transition: all 0.22s ease;
}

.pub-card:hover {
    border-left-color: var(--gold);
    box-shadow: 0 4px 22px rgba(0,0,0,0.07);
    transform: translateX(3px);
}

.pub-venue-tag {
    display: inline-block;
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0.09em;
    text-transform: uppercase;
    color: var(--blue);
    background: var(--blue-soft);
    padding: 2px 9px;
    border-radius: 4px;
    margin-bottom: 9px;
}

.pub-title-text {
    font-family: var(--font-h);
    font-size: 1.08rem;
    font-weight: 600;
    color: var(--ink);
    line-height: 1.48;
    margin-bottom: 6px;
}

.pub-authors-text {
    font-size: 0.95rem;
    color: var(--muted);
    line-height: 1.55;
    margin-bottom: 8px;
}

.pub-authors-text b,
.pub-authors-text strong {
    color: var(--ink);
    font-weight: 600;
}

.pub-highlight {
    font-size: 0.92rem;
    color: var(--red);
    font-weight: 700;
    margin-bottom: 10px;
}

.pub-badges {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

/* ── BADGES ─────────────────────────────────────────────── */
.badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    padding: 4px 13px;
    border-radius: 4px;
    text-decoration: none;
    text-transform: uppercase;
    transition: opacity 0.15s, transform 0.15s;
}

.badge:hover { opacity: 0.82; transform: translateY(-1px); }
.badge-pdf    { background: var(--blue);  color: #fff; }
.badge-arxiv  { background: var(--amber); color: #fff; }
.badge-slides { background: var(--green); color: #fff; }

/* ── PROFESSIONAL ───────────────────────────────────────── */
.reviewer-subtitle {
    font-family: var(--font-b);
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--muted);
    margin: 22px 0 10px;
}

.reviewer-subtitle:first-of-type { margin-top: 0; }

.course-role {
    font-size: 0.92rem;
    font-weight: 700;
    color: var(--ink);
    margin-top: 5px;
}

.reviewer-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0;
    list-style: none;
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
    background: var(--white);
}

.reviewer-grid li {
    font-size: 1rem;
    padding: 13px 20px;
    border-bottom: 1px solid var(--border);
    color: var(--text);
    border-right: 1px solid var(--border);
    line-height: 1.4;
}

.reviewer-grid li:nth-child(even) { border-right: none; }
.reviewer-grid li:nth-last-child(-n+2) { border-bottom: none; }

.reviewer-conf {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 14px;
}

.conf-chip {
    font-size: 0.88rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    padding: 5px 15px;
    background: var(--blue-soft);
    color: var(--blue);
    border-radius: 100px;
    border: 1px solid rgba(29,78,216,0.15);
}

.course-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px 28px;
    margin-bottom: 15px;
    font-size: 1.05rem;
    line-height: 1.68;
}

.course-card strong { color: var(--ink); }

.course-meta {
    font-size: 0.9rem;
    color: var(--muted);
    margin-top: 3px;
}

.talks-list {
    list-style: none;
}

.talk-entry {
    display: flex;
    gap: 25px;
    padding: 19px 0;
    border-bottom: 1px solid var(--border);
    font-size: 1.05rem;
    line-height: 1.65;
    align-items: flex-start;
}

.talk-entry:last-child { border-bottom: none; }

.talk-date-tag {
    font-size: 0.82rem;
    font-weight: 700;
    color: var(--blue);
    letter-spacing: 0.06em;
    text-transform: uppercase;
    white-space: nowrap;
    min-width: 74px;
    margin-top: 3px;
    background: var(--blue-soft);
    padding: 2px 7px;
    border-radius: 4px;
    flex-shrink: 0;
}

/* ── FOOTER ─────────────────────────────────────────────── */
.footer {
    background: var(--white);
    border-top: 1px solid var(--border);
    padding: 22px 72px;
    font-size: 0.78rem;
    color: var(--muted);
    text-align: center;
}

/* ── RESPONSIVE ─────────────────────────────────────────── */
@media (max-width: 1100px) {
    .content { padding: 48px 40px 88px; }
}

/* ── TABLET (≤ 900px) ───────────────────────────────────── */
@media (max-width: 900px) {
    :root { --sidebar-w: 240px; }
    html  { font-size: 15px; }
    .content { padding: 36px 28px 72px; }
    .sidebar { padding: 36px 20px 28px; }
    .sidebar-photo { width: 140px !important; height: 140px !important; }
}

/* ── MOBILE (≤ 768px) ───────────────────────────────────── */
@media (max-width: 768px) {
    html { font-size: 15px; }

    /* ── Nav: fixed bar, horizontally scrollable ── */
    .topnav {
        position: fixed;
        top: 0; left: 0; right: 0;
        height: 52px;
        justify-content: flex-start;
        padding: 0 12px;
        gap: 0;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: none;
        border-bottom: 1px solid var(--border);
    }
    .topnav::-webkit-scrollbar { display: none; }

    .topnav a {
        font-size: 0.85rem;
        padding: 6px 14px;
        white-space: nowrap;
        flex-shrink: 0;
        border-radius: 4px;
    }

    /* ── Layout: stack vertically ── */
    .page-wrapper {
        flex-direction: column;
        padding-top: 52px;      /* height of fixed mobile nav */
        min-height: 100vh;
    }

    /* ── Sidebar: compact grid header ── */
    .sidebar {
        position: relative;
        width: 100%;
        min-width: unset;
        height: auto;
        border-right: none;
        border-bottom: 2px solid var(--gold);
        top: 0;

        /* Grid layout: photo | name+role, then meta+links full-width */
        display: grid;
        grid-template-columns: 88px 1fr;
        grid-template-rows: auto auto auto auto;
        column-gap: 18px;
        row-gap: 0;
        padding: 20px 20px 16px;
    }

    .sidebar-photo {
        grid-column: 1;
        grid-row: 1 / 3;
        width: 88px !important;
        height: 88px !important;
        margin: 0;
        align-self: center;
        box-shadow: 0 0 0 5px rgba(197,128,42,0.15), 0 4px 16px rgba(0,0,0,0.3);
    }

    .sidebar-name {
        grid-column: 2;
        grid-row: 1;
        text-align: left;
        font-size: 1.25rem;
        align-self: end;
        margin-bottom: 3px;
    }

    .sidebar-role {
        grid-column: 2;
        grid-row: 2;
        text-align: left;
        font-size: 0.7rem;
        margin-bottom: 0;
        align-self: start;
    }

    .sidebar-hr {
        grid-column: 1 / 3;
        margin: 14px 0 10px;
    }

    .sidebar-meta {
        grid-column: 1 / 3;
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 6px 16px;
        margin-bottom: 10px;
    }

    .sidebar-meta li {
        font-size: 0.75rem;
        margin-bottom: 0;
    }

    .sidebar-links {
        grid-column: 1 / 3;
        flex-direction: row;
        flex-wrap: wrap;
        gap: 6px;
        margin-top: 0;
        padding-top: 10px;
        border-top: 1px solid rgba(255,255,255,0.1);
    }

    .sidebar-links a {
        font-size: 0.75rem;
        padding: 5px 10px;
        background: rgba(255,255,255,0.06);
    }

    /* ── Content ── */
    .content {
        padding: 28px 18px 60px;
        max-width: 100%;
    }

    .page-title { margin-bottom: 36px; }
    .page-title h1 { font-size: 1.9rem; }
    .page-title .tagline { font-size: 0.75rem; }

    .section { margin-bottom: 40px; }
    .section h2 { font-size: 1.3rem; }

    /* ── Research tags: smaller pills ── */
    .rtag { padding: 7px 14px; font-size: 0.875rem; }

    /* ── News: stack date + body ── */
    .news-item { flex-wrap: wrap; gap: 5px; }
    .news-body { font-size: 0.9rem; }

    /* ── Publication cards ── */
    .pub-card { padding: 16px 18px; }
    .pub-title-text { font-size: 0.95rem; }
    .pub-authors-text { font-size: 0.82rem; }

    /* ── Reviewer grid: single column ── */
    .reviewer-grid { grid-template-columns: 1fr; }
    .reviewer-grid li { border-right: none; }
    .reviewer-grid li:nth-last-child(-n+2) { border-bottom: 1px solid var(--border); }
    .reviewer-grid li:last-child { border-bottom: none; }

    /* ── Talks: stack date tag ── */
    .talk-entry { flex-direction: column; gap: 6px; padding: 14px 0; }

    /* ── Footer ── */
    .footer { padding: 16px 18px; font-size: 0.72rem; }
}

/* ── PHONE (≤ 480px) ────────────────────────────────────── */
@media (max-width: 480px) {
    html { font-size: 14px; }

    .topnav a { font-size: 0.8rem; padding: 6px 11px; }

    .sidebar {
        grid-template-columns: 76px 1fr;
        column-gap: 14px;
        padding: 16px 16px 14px;
    }

    .sidebar-photo {
        width: 76px !important;
        height: 76px !important;
    }

    .sidebar-name { font-size: 1.1rem; }

    .sidebar-meta {
        grid-template-columns: 1fr;   /* single column on small phones */
    }

    .content { padding: 22px 14px 52px; }

    .page-title h1 { font-size: 1.65rem; }

    .section h2 { font-size: 1.2rem; }

    .news-item { flex-direction: column; gap: 4px; }
    .news-tag { align-self: flex-start; }

    .research-tags { gap: 7px; }
    .rtag { padding: 6px 12px; font-size: 0.8rem; }

    .pub-card { padding: 13px 14px; }

    .conf-chip { font-size: 0.78rem; padding: 4px 10px; }
    .course-card { padding: 14px 16px; }
    .awards-list li { padding: 11px 14px; }
}