@import url('https://fonts.googleapis.com/css2?family=DM+Serif+Display:ital@0;1&family=DM+Sans:ital,opsz,wght@0,9..40,300;0,9..40,400;0,9..40,500;0,9..40,600;0,9..40,700;1,9..40,400&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
    --bg-deep: #0a0f1a;
    --bg-section: #0e1422;
    --bg-card: rgba(255, 255, 255, 0.03);
    --bg-card-hover: rgba(255, 255, 255, 0.06);
    --text-primary: #e8ecf4;
    --text-secondary: #8a92a6;
    --text-muted: #555d73;
    --accent: #4de8c2;
    --accent-dim: rgba(77, 232, 194, 0.12);
    --accent-blue: #6c8cff;
    --accent-blue-dim: rgba(108, 140, 255, 0.12);
    --accent-warm: #c9a86c;
    --accent-warm-dim: rgba(201, 168, 108, 0.10);
    --border: rgba(255, 255, 255, 0.06);
    --border-hover: rgba(255, 255, 255, 0.12);
    --radius: 14px;
    --radius-sm: 8px;
    --side-nav-w: 72px;
    --font-display: 'DM Serif Display', Georgia, 'Noto Serif SC', serif;
    --font-body: 'DM Sans', 'Noto Sans SC', system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    --transition: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-body);
    background: var(--bg-deep);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
}

::selection {
    background: var(--accent);
    color: var(--bg-deep);
}

/* ===== 侧边导航 ===== */
.side-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--side-nav-w);
    height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    padding: 24px 0;
    z-index: 100;
    border-right: 1px solid var(--border);
    background: rgba(10, 15, 26, 0.85);
    backdrop-filter: blur(20px);
}

.nav-logo a {
    font-family: var(--font-display);
    font-size: 1.1rem;
    color: var(--accent);
    text-decoration: none;
    letter-spacing: 1px;
}

.nav-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.nav-links a {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    text-decoration: none;
    color: var(--text-muted);
    border-radius: 50%;
    transition: var(--transition);
}

.nav-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--text-muted);
    transition: var(--transition);
}

.nav-label {
    position: absolute;
    left: calc(100% + 12px);
    white-space: nowrap;
    font-size: 0.78rem;
    font-weight: 500;
    color: var(--text-secondary);
    background: var(--bg-section);
    padding: 4px 10px;
    border-radius: 6px;
    border: 1px solid var(--border);
    opacity: 0;
    pointer-events: none;
    transform: translateX(-4px);
    transition: var(--transition);
}

.nav-links a:hover .nav-label,
.nav-links a.active .nav-label {
    opacity: 1;
    transform: translateX(0);
}

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

.nav-links a:hover .nav-dot,
.nav-links a.active .nav-dot {
    background: var(--accent);
    box-shadow: 0 0 10px var(--accent);
    transform: scale(1.4);
}

.nav-footer a {
    color: var(--text-muted);
    font-size: 1rem;
    transition: var(--transition);
}

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

/* ===== 移动端导航 ===== */
.mobile-nav {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 56px;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
    z-index: 200;
    background: rgba(10, 15, 26, 0.92);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
}

.mobile-nav-brand a {
    font-family: var(--font-display);
    color: var(--text-primary);
    text-decoration: none;
    font-size: 1rem;
}

.mobile-nav-toggle {
    width: 28px;
    height: 20px;
    background: none;
    border: none;
    cursor: pointer;
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

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

.mobile-nav-toggle.open span:nth-child(1) {
    transform: translateY(9px) rotate(45deg);
}

.mobile-nav-toggle.open span:nth-child(2) {
    opacity: 0;
}

.mobile-nav-toggle.open span:nth-child(3) {
    transform: translateY(-9px) rotate(-45deg);
}

.mobile-menu {
    display: none;
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(10, 15, 26, 0.98);
    backdrop-filter: blur(20px);
    z-index: 199;
    padding: 32px 24px;
}

.mobile-menu.open {
    display: block;
}

.mobile-menu ul {
    list-style: none;
}

.mobile-menu li {
    border-bottom: 1px solid var(--border);
}

.mobile-menu a {
    display: block;
    padding: 16px 0;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 1.15rem;
    font-weight: 500;
    transition: var(--transition);
}

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

/* ===== 主内容 ===== */
.main-content {
    margin-left: var(--side-nav-w);
}

/* ===== Hero 区域 ===== */
.hero-section {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    padding: 60px 48px;
}

#particleCanvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 900px;
}

.hero-tag {
    display: inline-block;
    font-size: 0.82rem;
    font-weight: 500;
    color: var(--accent);
    background: var(--accent-dim);
    padding: 6px 16px;
    border-radius: 999px;
    margin-bottom: 28px;
    letter-spacing: 0.3px;
    border: 1px solid rgba(77, 232, 194, 0.15);
}

.hero-name {
    margin-bottom: 24px;
}

.name-cn {
    display: block;
    font-family: var(--font-display);
    font-size: clamp(3.4rem, 6.8vw, 5.2rem);
    line-height: 1.1;
    color: var(--text-primary);
    letter-spacing: -0.5px;
}

.name-en {
    display: block;
    font-family: var(--font-body);
    font-size: clamp(1.05rem, 2.2vw, 1.45rem);
    font-weight: 300;
    color: var(--text-secondary);
    margin-top: 8px;
    letter-spacing: 2px;
    text-transform: uppercase;
}

.hero-desc {
    font-size: 1.18rem;
    line-height: 1.85;
    color: var(--text-secondary);
    margin-bottom: 36px;
    max-width: 720px;
}

.hero-desc .highlight {
    color: var(--accent);
    font-weight: 600;
}

.hero-actions {
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
}

.btn-primary {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--bg-deep);
    background: var(--accent);
    border: none;
    border-radius: var(--radius-sm);
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    letter-spacing: 0.2px;
}

.btn-primary:hover {
    background: #6df0d2;
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(77, 232, 194, 0.25);
}

.btn-ghost {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-primary);
    background: transparent;
    border: 1px solid var(--border-hover);
    border-radius: var(--radius-sm);
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
}

.btn-ghost:hover {
    background: var(--bg-card-hover);
    border-color: var(--accent);
    color: var(--accent);
}

.scroll-hint {
    position: absolute;
    bottom: 36px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    color: var(--text-muted);
    font-size: 0.72rem;
    letter-spacing: 2px;
    text-transform: uppercase;
}

.scroll-line {
    width: 1px;
    height: 40px;
    background: linear-gradient(to bottom, var(--accent), transparent);
    animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
    0%, 100% { opacity: 0.3; transform: scaleY(0.6); }
    50% { opacity: 1; transform: scaleY(1); }
}

/* ===== 内容段落 ===== */
.content-section {
    padding: 100px 48px;
    border-top: 1px solid var(--border);
}

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

.section-header {
    display: flex;
    align-items: baseline;
    gap: 16px;
    margin-bottom: 48px;
}

.section-num {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    font-weight: 500;
    color: var(--accent);
    opacity: 0.6;
}

.section-title {
    font-family: var(--font-display);
    font-size: clamp(2rem, 3.8vw, 2.8rem);
    color: var(--text-primary);
    letter-spacing: -0.3px;
}

/* ===== 关于 ===== */
.about-grid {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 24px;
}

.about-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    transition: var(--transition);
}

.about-card:hover {
    border-color: var(--border-hover);
    background: var(--bg-card-hover);
}

.about-bio p {
    color: var(--text-secondary);
    font-size: 0.98rem;
    line-height: 1.85;
    margin-bottom: 16px;
}

.about-bio p:last-child {
    margin-bottom: 0;
}

.about-keywords h3 {
    font-family: var(--font-body);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1.5px;
    margin-bottom: 20px;
}

.keyword-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.kw-tag {
    display: inline-block;
    padding: 6px 14px;
    font-size: 0.82rem;
    font-weight: 500;
    color: var(--accent);
    background: var(--accent-dim);
    border: 1px solid rgba(77, 232, 194, 0.12);
    border-radius: 999px;
    transition: var(--transition);
}

.kw-tag:hover {
    background: rgba(77, 232, 194, 0.2);
    border-color: rgba(77, 232, 194, 0.3);
}

/* ===== 教育背景 ===== */
.edu-timeline {
    display: flex;
    flex-direction: column;
    gap: 0;
    position: relative;
    padding-left: 0;
}

.edu-item {
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 20px 0;
    position: relative;
}

.edu-item:not(:last-child) {
    border-bottom: 1px solid var(--border);
}

.edu-icon {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    background: var(--accent-dim);
    color: var(--accent);
    font-size: 1rem;
    flex-shrink: 0;
}

.edu-visit .edu-icon {
    background: var(--accent-blue-dim);
    color: var(--accent-blue);
}

.edu-content {
    flex: 1;
}

.edu-degree {
    font-weight: 600;
    font-size: 1.02rem;
    color: var(--text-primary);
    margin-bottom: 2px;
}

.edu-school {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* ===== 研究方向 ===== */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 16px;
}

.research-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px 22px;
    text-align: center;
    transition: var(--transition);
    cursor: default;
}

.research-card:hover {
    background: var(--bg-card-hover);
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: 0 12px 40px rgba(77, 232, 194, 0.08);
}

.research-icon {
    width: 52px;
    height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 16px;
    border-radius: 14px;
    background: var(--accent-dim);
    color: var(--accent);
    font-size: 1.25rem;
    transition: var(--transition);
}

.research-card:hover .research-icon {
    background: rgba(77, 232, 194, 0.2);
    transform: scale(1.08);
}

.research-card h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.research-card p {
    font-size: 0.82rem;
    color: var(--text-muted);
    line-height: 1.6;
}

/* ===== 教学课程 ===== */
.teaching-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
}

.teaching-card {
    position: relative;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px 24px;
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
    cursor: pointer;
    overflow: hidden;
}

.teaching-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent), var(--accent-blue));
    opacity: 0;
    transition: var(--transition);
}

.teaching-card:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    transform: translateY(-2px);
}

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

.teaching-badge {
    display: inline-block;
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--accent-blue);
    background: var(--accent-blue-dim);
    padding: 3px 10px;
    border-radius: 999px;
    margin-bottom: 14px;
    letter-spacing: 0.3px;
}

.teaching-card h4 {
    font-size: 1.08rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.teaching-card p {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.6;
}

.teaching-arrow {
    position: absolute;
    top: 28px;
    right: 24px;
    color: var(--text-muted);
    font-size: 0.85rem;
    transition: var(--transition);
}

.teaching-card:hover .teaching-arrow {
    color: var(--accent);
    transform: translateX(4px);
}

.teaching-badge--warm {
    color: var(--accent-warm);
    background: var(--accent-warm-dim);
}

/* 在线教程难度标识色 */
.teaching-badge--beginner {
    color: var(--accent-warm);
    background: var(--accent-warm-dim);
}

.teaching-badge--intermediate {
    color: var(--accent-blue);
    background: var(--accent-blue-dim);
}

.teaching-badge--advanced {
    color: var(--accent-red, #e74c3c);
    background: rgba(231, 76, 60, 0.12);
}

.teaching-card-title-icon {
    font-size: 0.85rem;
    margin-right: 6px;
    opacity: 0.6;
}

.teaching-group-divider {
    display: flex;
    align-items: center;
    gap: 16px;
    margin: 28px 0 16px;
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--text-muted);
    letter-spacing: 2px;
    text-transform: uppercase;
}

.teaching-group-divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
}

/* ===== 论文列表 ===== */
.pub-year-group {
    margin-bottom: 8px;
}

.pub-year-toggle {
    display: flex;
    align-items: center;
    gap: 12px;
    width: 100%;
    padding: 14px 18px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.pub-year-toggle:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
}

.pub-year-toggle[aria-expanded="true"] {
    border-bottom-left-radius: 0;
    border-bottom-right-radius: 0;
    border-color: var(--accent);
    border-bottom-color: var(--border);
}

.pub-year-toggle[aria-expanded="true"] i {
    transform: rotate(180deg);
}

.pub-year-num {
    font-family: var(--font-mono);
    color: var(--accent);
    font-weight: 500;
}

.pub-year-count {
    font-size: 0.78rem;
    font-weight: 400;
    color: var(--text-muted);
    margin-left: auto;
}

.pub-year-toggle i {
    color: var(--text-muted);
    font-size: 0.75rem;
    transition: var(--transition);
}

.pub-list {
    display: none;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-top: none;
    border-radius: 0 0 var(--radius-sm) var(--radius-sm);
    padding: 8px 0;
}

.pub-item {
    padding: 12px 18px;
    border-left: 2px solid transparent;
    transition: var(--transition);
}

.pub-item:hover {
    background: rgba(77, 232, 194, 0.03);
    border-left-color: var(--accent);
}

.pub-item p {
    font-size: 0.88rem;
    line-height: 1.75;
    color: var(--text-secondary);
}

.pub-item strong {
    color: var(--accent);
    font-weight: 600;
}

.pub-item em {
    font-style: normal;
    color: var(--accent-blue);
    font-weight: 500;
}

/* 论文标题：斜体显示，与期刊/会议名（em）区分开 */
.pub-item .pub-title {
    font-style: italic;
    color: inherit;
    font-weight: 400;
}

/* ===== 科研项目 ===== */
.projects-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 32px;
}

.projects-col-title {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1.5px;
    margin-bottom: 16px;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 20px;
    margin-bottom: 12px;
    transition: var(--transition);
}

.project-card:hover {
    border-color: var(--border-hover);
    background: var(--bg-card-hover);
}

.project-tag {
    display: inline-block;
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--accent);
    background: var(--accent-dim);
    padding: 2px 10px;
    border-radius: 999px;
    margin-bottom: 10px;
}

.project-card h4 {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.5;
    margin-bottom: 6px;
}

.project-period {
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-muted);
}

/* ===== 页脚 ===== */
.site-footer {
    margin-left: var(--side-nav-w);
    padding: 28px 48px;
    border-top: 1px solid var(--border);
}

.footer-inner p {
    font-size: 0.82rem;
    color: var(--text-muted);
    text-align: center;
}

/* ===== 滚动动画 ===== */
.reveal {
    opacity: 0;
    transform: translateY(28px);
    transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1),
                transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

.reveal.revealed {
    opacity: 1;
    transform: translateY(0);
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
    .side-nav {
        display: none;
    }

    .mobile-nav {
        display: flex;
    }

    .main-content {
        margin-left: 0;
        padding-top: 56px;
    }

    .site-footer {
        margin-left: 0;
    }

    .hero-section {
        padding: 40px 24px;
    }

    .content-section {
        padding: 60px 24px;
    }

    .site-footer {
        padding: 24px;
    }

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

    .research-grid {
        grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    }

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

    .projects-layout {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 600px) {
    .hero-section {
        padding: 32px 20px;
        min-height: calc(100vh - 56px);
    }

    .name-cn {
        font-size: 2.4rem;
    }

    .hero-desc {
        font-size: 0.95rem;
    }

    .hero-desc br {
        display: none;
    }

    .content-section {
        padding: 48px 20px;
    }

    .section-header {
        margin-bottom: 32px;
    }

    .research-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }

    .research-card {
        padding: 20px 14px;
    }

    .scroll-hint {
        display: none;
    }
}