/* ===== CSS Variables ===== */
:root {
    --bg: #0a0a0f;
    --bg-alt: #111118;
    --surface: #1a1a24;
    --surface-hover: #22222f;
    --border: #2a2a3a;
    --text: #e4e4ed;
    --text-secondary: #9494a8;
    --accent: #6366f1;
    --accent-light: #818cf8;
    --accent-glow: rgba(99, 102, 241, 0.15);
    --gold: #f59e0b;
    --gold-glow: rgba(245, 158, 11, 0.15);
    --green: #10b981;
    --zhihu-blue: #0066ff;
    --radius: 12px;
    --radius-sm: 8px;
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

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

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

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(10, 10, 15, 0.85);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid transparent;
    transition: border-color var(--transition), background var(--transition);
}

.navbar.scrolled {
    border-bottom-color: var(--border);
    background: rgba(10, 10, 15, 0.95);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text) !important;
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    position: relative;
    padding: 0.25rem 0;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent);
    transition: width var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--text);
}

.nav-links a:hover::after,
.nav-links a.active::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text);
    transition: var(--transition);
}

/* ===== Hero ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    padding: 6rem 2rem 4rem;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 60% 50% at 20% 50%, rgba(99, 102, 241, 0.08), transparent),
        radial-gradient(ellipse 40% 40% at 80% 30%, rgba(245, 158, 11, 0.05), transparent);
    pointer-events: none;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: 4rem;
    width: 100%;
    position: relative;
    z-index: 1;
}

.hero-text {
    flex: 1;
}

.hero-greeting {
    font-size: 1rem;
    color: var(--accent-light);
    font-weight: 500;
    margin-bottom: 0.5rem;
    letter-spacing: 1px;
    text-transform: uppercase;
}

.hero-name {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 1rem;
    letter-spacing: -1px;
}

.hero-cn {
    display: inline-block;
    font-size: 0.6em;
    color: var(--text-secondary);
    font-weight: 400;
    vertical-align: middle;
    margin-left: 0.5rem;
}

.hero-tagline {
    font-size: 1.15rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    max-width: 520px;
}

.hero-affiliation {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.hero-affiliation i {
    color: var(--accent-light);
    margin-right: 0.5rem;
}

.hero-stats {
    display: flex;
    gap: 2.5rem;
    margin-bottom: 2rem;
}

.stat {
    display: flex;
    flex-direction: column;
}

.stat-number {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text);
    font-family: 'JetBrains Mono', monospace;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.hero-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.7rem 1.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition);
    border: 1px solid transparent;
}

.btn-primary {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
}

.btn-primary:hover {
    background: var(--accent-light);
    color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.3);
}

.btn-secondary {
    background: transparent;
    color: var(--text);
    border-color: var(--border);
}

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent-light);
    transform: translateY(-2px);
}

.btn-zhihu {
    background: var(--zhihu-blue);
    color: #fff !important;
    border-color: var(--zhihu-blue);
}

.btn-zhihu:hover {
    background: #0052cc;
    color: #fff !important;
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(0, 102, 255, 0.3);
}

/* Hero Visual */
.hero-visual {
    flex-shrink: 0;
}

.avatar-ring {
    width: 260px;
    height: 260px;
    border-radius: 50%;
    background: conic-gradient(from 0deg, var(--accent), var(--gold), var(--green), var(--accent));
    padding: 4px;
    animation: ring-rotate 8s linear infinite;
}

@keyframes ring-rotate {
    to { transform: rotate(360deg); }
}

.avatar-placeholder {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background: var(--surface);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 5rem;
    color: var(--text-secondary);
}

.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.75rem;
    letter-spacing: 2px;
    text-transform: uppercase;
    animation: bounce 2s ease-in-out infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(8px); }
}

/* ===== Sections ===== */
.section {
    padding: 5rem 2rem;
}

.section-alt {
    background: var(--bg-alt);
}

.container {
    max-width: 1100px;
    margin: 0 auto;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: -0.5px;
}

.section-subtitle {
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    font-size: 1rem;
}

/* ===== About ===== */
.about-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 3rem;
    align-items: start;
    margin-bottom: 3rem;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

.about-text strong {
    color: var(--text);
}

.about-interests h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text);
}

.interest-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tag {
    padding: 0.4rem 0.9rem;
    background: var(--accent-glow);
    color: var(--accent-light);
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

/* ===== Timeline ===== */
.timeline-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text);
}

.timeline {
    position: relative;
    padding-left: 2rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 7px;
    top: 6px;
    bottom: 6px;
    width: 2px;
    background: var(--border);
}

.timeline-item {
    position: relative;
    padding-bottom: 1.75rem;
    display: grid;
    grid-template-columns: 140px 1fr;
    gap: 1rem;
    align-items: start;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-dot {
    position: absolute;
    left: -2rem;
    top: 5px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--surface);
    border: 2px solid var(--border);
    z-index: 1;
    transition: all var(--transition);
}

.timeline-item.current .timeline-dot {
    border-color: var(--accent);
    background: var(--accent);
    box-shadow: 0 0 12px rgba(99, 102, 241, 0.4);
}

.timeline-item:hover .timeline-dot {
    border-color: var(--accent-light);
    transform: scale(1.2);
}

.timeline-date {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--accent-light);
    white-space: nowrap;
    padding-top: 0.1rem;
}

.timeline-body h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.2rem;
}

.timeline-body p {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* ===== Highlights ===== */
.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.5rem;
}

.highlight-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.75rem;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
}

.highlight-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--accent);
    opacity: 0;
    transition: opacity var(--transition);
}

.highlight-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: 0 8px 32px rgba(99, 102, 241, 0.1);
}

.highlight-card:hover::before {
    opacity: 1;
}

.highlight-card.spotlight {
    border-color: rgba(245, 158, 11, 0.3);
    background: linear-gradient(135deg, var(--surface), rgba(245, 158, 11, 0.03));
}

.highlight-card.spotlight::before {
    background: var(--gold);
    opacity: 1;
}

.highlight-card.spotlight:hover {
    border-color: var(--gold);
    box-shadow: 0 8px 32px rgba(245, 158, 11, 0.1);
}

.card-badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--accent-glow);
    color: var(--accent-light);
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.5px;
    margin-bottom: 0.75rem;
}

.highlight-card.spotlight .card-badge {
    background: var(--gold-glow);
    color: var(--gold);
}

.card-citations {
    float: right;
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-family: 'JetBrains Mono', monospace;
}

.card-citations i {
    margin-right: 0.25rem;
    font-size: 0.7rem;
}

.highlight-card h3 {
    font-size: 1.05rem;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 0.5rem;
}

.card-authors {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.card-desc {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* ===== Publications ===== */
.pub-filters {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 2rem;
}

.filter-btn {
    padding: 0.5rem 1.25rem;
    background: var(--surface);
    color: var(--text-secondary);
    border: 1px solid var(--border);
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    font-family: inherit;
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent);
}

.pub-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.pub-item {
    display: flex;
    gap: 1.5rem;
    padding: 1.25rem 1.5rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    transition: all var(--transition);
    align-items: flex-start;
}

.pub-item:hover {
    border-color: var(--accent);
    transform: translateX(4px);
}

.pub-item.hidden {
    display: none;
}

.pub-year {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--accent-light);
    white-space: nowrap;
    padding-top: 0.15rem;
    min-width: 40px;
}

.pub-content h4 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
    line-height: 1.4;
}

.pub-authors {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.35rem;
}

.pub-venue {
    display: inline-block;
    font-size: 0.75rem;
    color: var(--accent-light);
    background: var(--accent-glow);
    padding: 0.15rem 0.6rem;
    border-radius: 10px;
    margin-right: 0.5rem;
}

.pub-cite {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-family: 'JetBrains Mono', monospace;
}

/* ===== Zhihu Section ===== */
.zhihu-profile {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem;
    margin-bottom: 2.5rem;
}

.zhihu-info h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.zhihu-bio {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.zhihu-stats {
    display: flex;
    gap: 2rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.zhihu-stats i {
    color: var(--zhihu-blue);
    margin-right: 0.5rem;
}

.zhihu-articles h3 {
    font-size: 1.25rem;
    margin-bottom: 1.25rem;
}

.article-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.article-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    transition: all var(--transition);
    color: var(--text) !important;
}

.article-item:hover {
    border-color: var(--zhihu-blue);
    transform: translateX(6px);
    box-shadow: 0 4px 16px rgba(0, 102, 255, 0.08);
}

.article-icon {
    flex-shrink: 0;
    width: 36px;
    height: 36px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 102, 255, 0.1);
    color: var(--zhihu-blue);
    font-size: 0.9rem;
}

.article-item.hot .article-icon {
    background: rgba(245, 158, 11, 0.12);
    color: var(--gold);
}

.article-info {
    flex: 1;
    min-width: 0;
}

.article-info h4 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 0.15rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.article-info p {
    font-size: 0.8rem;
    color: var(--text-secondary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.article-arrow {
    flex-shrink: 0;
    color: var(--text-secondary);
    font-size: 0.8rem;
    transition: all var(--transition);
}

.article-item:hover .article-arrow {
    color: var(--zhihu-blue);
    transform: translateX(3px);
}

/* ===== Contact ===== */
.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 1.25rem;
}

.contact-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 2rem 1.5rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: all var(--transition);
    color: var(--text) !important;
}

.contact-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: var(--shadow);
}

.contact-card i {
    font-size: 1.75rem;
    color: var(--accent-light);
    margin-bottom: 0.75rem;
}

.contact-card span {
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.contact-card p {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* ===== Footer ===== */
.footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
    border-top: 1px solid var(--border);
}

/* ===== Animations ===== */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: rgba(10, 10, 15, 0.98);
        flex-direction: column;
        padding: 1rem 2rem 2rem;
        gap: 1rem;
        border-bottom: 1px solid var(--border);
    }

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

    .hero-content {
        flex-direction: column-reverse;
        text-align: center;
    }

    .hero-stats {
        justify-content: center;
    }

    .hero-links {
        justify-content: center;
    }

    .avatar-ring {
        width: 180px;
        height: 180px;
    }

    .avatar-placeholder {
        font-size: 3.5rem;
    }

    .about-content {
        grid-template-columns: 1fr;
    }

    .timeline-item {
        grid-template-columns: 1fr;
        gap: 0.25rem;
        padding-left: 0.5rem;
    }

    .timeline-date {
        font-size: 0.75rem;
    }

    .highlights-grid {
        grid-template-columns: 1fr;
    }

    .pub-item {
        flex-direction: column;
        gap: 0.5rem;
    }

    .contact-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 5rem 1rem 3rem;
    }

    .section {
        padding: 3rem 1rem;
    }

    .hero-stats {
        gap: 1.5rem;
    }

    .contact-grid {
        grid-template-columns: 1fr;
    }
}