/* ============================================================
   个人主页 · 清新学术风
   ============================================================ */

/* ---------- CSS Variables ---------- */
:root {
  --color-primary: #4361ee;
  --color-primary-light: #6c83f4;
  --color-primary-dark: #3047c9;
  --color-primary-bg: #eef1ff;
  --color-accent: #06d6a0;

  --color-bg: #f7f8fc;
  --color-bg-alt: #ffffff;
  --color-surface: #ffffff;
  --color-border: #e2e6ef;

  --color-text: #2d3142;
  --color-text-secondary: #6b7194;
  --color-text-light: #9aa0b9;

  --font-sans: 'Noto Sans SC', 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;

  --shadow-sm: 0 1px 3px rgba(45, 49, 66, 0.06);
  --shadow-md: 0 4px 16px rgba(45, 49, 66, 0.08);
  --shadow-lg: 0 8px 32px rgba(45, 49, 66, 0.1);

  --radius: 12px;
  --radius-sm: 8px;
  --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: 70px;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

a:hover {
  color: var(--color-primary-dark);
}

img {
  max-width: 100%;
  display: block;
}

/* ---------- Utility ---------- */
.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

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

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  text-align: center;
  color: var(--color-text);
  margin-bottom: 8px;
}

.section-divider {
  width: 40px;
  height: 3px;
  background: var(--color-primary);
  border-radius: 2px;
  margin: 0 auto 48px;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 24px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 500;
  transition: all var(--transition);
  cursor: pointer;
  border: 2px solid transparent;
}

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

.btn-primary:hover {
  background: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-outline {
  background: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.btn-outline:hover {
  background: var(--color-primary);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

/* ============================================================
   Navigation
   ============================================================ */
#navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(247, 248, 252, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow var(--transition);
}

#navbar.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.nav-logo {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: -0.5px;
}

.nav-logo:hover {
  color: var(--color-primary-dark);
}

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

.nav-links a {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--transition);
}

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

.nav-blog-link {
  color: var(--color-primary) !important;
  border: 1.5px solid var(--color-primary);
  border-radius: 6px !important;
}

.nav-blog-link:hover {
  background: var(--color-primary) !important;
  color: #fff !important;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.4rem;
  color: var(--color-text);
  cursor: pointer;
  padding: 4px;
}

/* ============================================================
   Hero Section
   ============================================================ */
#hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 24px 60px;
  background: linear-gradient(160deg, #f7f8fc 0%, #eef1ff 50%, #f0fdf9 100%);
  position: relative;
}

.hero-content {
  max-width: 600px;
}

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

.avatar-placeholder {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: var(--color-primary-bg);
  border: 3px solid var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto;
  font-size: 3rem;
  color: var(--color-primary);
}

.avatar-img {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  border: 3px solid var(--color-primary);
  object-fit: cover;
  margin: 0 auto;
}

.hero-name {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 8px;
}

.hero-title {
  font-size: 1.15rem;
  color: var(--color-primary);
  font-weight: 500;
  margin-bottom: 12px;
}

.hero-subtitle {
  font-size: 1rem;
  color: var(--color-text-secondary);
  margin-bottom: 28px;
  line-height: 1.6;
}

.hero-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin-bottom: 32px;
}

.hero-social {
  display: flex;
  gap: 16px;
  justify-content: center;
}

.hero-social a {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  transition: all var(--transition);
}

.hero-social a:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.hero-scroll-hint {
  position: absolute;
  bottom: 32px;
  animation: bounce 2s infinite;
}

.hero-scroll-hint a {
  font-size: 1.4rem;
  color: var(--color-text-light);
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
  40% { transform: translateY(-8px); }
  60% { transform: translateY(-4px); }
}

/* ============================================================
   About Section
   ============================================================ */
.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: start;
}

.about-text p {
  margin-bottom: 16px;
  color: var(--color-text-secondary);
  font-size: 0.95rem;
}

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

.about-info-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.info-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px;
  background: var(--color-bg);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  transition: all var(--transition);
}

.info-card:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-sm);
}

.info-card i {
  font-size: 1.5rem;
  color: var(--color-primary);
  flex-shrink: 0;
}

.info-card div {
  display: flex;
  flex-direction: column;
}

.info-label {
  font-size: 0.75rem;
  color: var(--color-text-light);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.info-value {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text);
}

/* ============================================================
   Education & Timeline
   ============================================================ */
.timeline {
  position: relative;
  padding-left: 32px;
  margin-bottom: 48px;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--color-border);
}

.timeline-item {
  position: relative;
  margin-bottom: 32px;
}

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

.timeline-dot {
  position: absolute;
  left: -32px;
  top: 8px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-primary);
  border: 3px solid var(--color-primary-bg);
  z-index: 1;
}

.timeline-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
  transition: all var(--transition);
}

.timeline-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary-light);
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 4px;
}

.timeline-header h3 {
  font-size: 1.1rem;
  font-weight: 600;
}

.timeline-date {
  font-size: 0.85rem;
  color: var(--color-primary);
  font-weight: 500;
  white-space: nowrap;
}

.timeline-degree {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-bottom: 8px;
}

.timeline-detail {
  font-size: 0.88rem;
  color: var(--color-text-light);
  line-height: 1.6;
}

/* Publications */
.subsection-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.subsection-title i {
  color: var(--color-primary);
}

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

.publication-list li {
  padding: 16px 20px;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  margin-bottom: 12px;
  transition: all var(--transition);
}

.publication-list li:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-sm);
}

.pub-title {
  display: block;
  font-weight: 600;
  font-size: 0.93rem;
  margin-bottom: 4px;
}

.pub-info {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* ============================================================
   Skills Section
   ============================================================ */
.skills-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.skill-category {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all var(--transition);
}

.skill-category:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary-light);
}

.skill-category h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.skill-category h3 i {
  color: var(--color-primary);
  font-size: 1.15rem;
}

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

.tag {
  padding: 5px 14px;
  background: var(--color-primary-bg);
  color: var(--color-primary);
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 500;
  transition: all var(--transition);
  cursor: default;
}

.tag:hover {
  background: var(--color-primary);
  color: #fff;
  transform: translateY(-1px);
}

/* ============================================================
   Projects Section
   ============================================================ */
.projects-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
}

.project-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary-light);
  transform: translateY(-2px);
}

.project-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background: var(--color-primary-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  color: var(--color-primary);
  margin-bottom: 16px;
}

.project-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.project-card p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin-bottom: 16px;
  flex: 1;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 16px;
}

.project-tags span {
  padding: 3px 10px;
  font-size: 0.75rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  color: var(--color-text-light);
  font-weight: 500;
}

.project-links {
  display: flex;
  gap: 16px;
}

.project-links a {
  font-size: 0.85rem;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  color: var(--color-primary);
  font-weight: 500;
}

.project-links a:hover {
  color: var(--color-primary-dark);
}

/* ============================================================
   Contact Section
   ============================================================ */
.contact-intro {
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  margin-bottom: 36px;
}

.contact-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 20px;
}

.contact-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 8px;
  padding: 28px 16px;
  width: 200px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  transition: all var(--transition);
}

.contact-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.contact-card i {
  font-size: 1.8rem;
  color: var(--color-primary);
}

.contact-label {
  font-size: 0.8rem;
  color: var(--color-text-light);
  font-weight: 500;
}

.contact-value {
  font-size: 0.88rem;
  color: var(--color-text);
  font-weight: 600;
  word-break: break-all;
}

/* ============================================================
   Footer
   ============================================================ */
footer {
  padding: 32px 0;
  text-align: center;
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
}

footer p {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

.footer-sub {
  margin-top: 4px;
  font-size: 0.8rem;
}

.footer-icp {
  margin-top: 6px;
  font-size: 0.78rem;
}

.footer-icp a {
  color: var(--color-text-light);
  text-decoration: none;
  transition: color var(--transition);
}

.footer-icp a:hover {
  color: var(--color-primary);
}

/* ============================================================
   Scroll-triggered Animations
   ============================================================ */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ============================================================
   Responsive Design
   ============================================================ */
@media (max-width: 768px) {

  .nav-toggle {
    display: block;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: rgba(247, 248, 252, 0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: 16px 24px;
    gap: 4px;
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
  }

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

  .nav-links a {
    padding: 10px 14px;
    width: 100%;
  }

  .hero-name {
    font-size: 2rem;
  }

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

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

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

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

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

  .section {
    padding: 60px 0;
  }

  .timeline-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }
}

@media (max-width: 480px) {

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

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

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }
}