/* ===== CSS Reset & Base ===== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  color: #1e293b;
  background: #ffffff;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { text-decoration: none; color: inherit; }
img { max-width: 100%; display: block; }

/* ===== Utility ===== */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.gradient-line {
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, #6366f1, #f97316);
  margin: 16px auto 0;
  border-radius: 2px;
}
.section-title {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  color: #0f172a;
}
.section-subtitle {
  text-align: center;
  color: #64748b;
  margin-top: 12px;
  font-size: 0.95rem;
}
.btn-primary {
  display: inline-block;
  padding: 12px 32px;
  background: #f97316;
  color: #fff;
  border-radius: 8px;
  font-weight: 500;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
  font-size: 0.95rem;
}
.btn-primary:hover { background: #ea580c; transform: translateY(-2px); box-shadow: 0 8px 25px rgba(249, 115, 22, 0.3); }
.btn-outline {
  display: inline-block;
  padding: 10px 28px;
  border: 1px solid #cbd5e1;
  color: #334155;
  border-radius: 8px;
  font-weight: 500;
  transition: all 0.3s ease;
  background: transparent;
  cursor: pointer;
  font-size: 0.9rem;
}
.btn-outline:hover { border-color: #f97316; color: #f97316; }

/* ===== Navigation ===== */
.navbar {
  background: #0f172a;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0,0,0,0.15);
}
.nav-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.nav-logo { display: flex; align-items: center; gap: 12px; }
.nav-logo-icon {
  width: 36px; height: 36px;
  background: linear-gradient(135deg, #6366f1, #f97316);
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 700; font-size: 0.85rem;
}
.nav-logo-text { color: #fff; }
.nav-logo-text .cn { font-size: 1rem; font-weight: 600; line-height: 1.3; }
.nav-logo-text .en { font-size: 0.7rem; color: #94a3b8; line-height: 1.2; }
.nav-links { display: flex; align-items: center; gap: 4px; list-style: none; }
.nav-links a {
  padding: 8px 14px;
  color: #cbd5e1;
  font-size: 0.88rem;
  border-radius: 6px;
  transition: all 0.25s ease;
  white-space: nowrap;
}
.nav-links a:hover, .nav-links a.active { color: #fff; background: rgba(255,255,255,0.08); }
.nav-mobile-toggle { display: none; background: none; border: none; color: #fff; cursor: pointer; padding: 4px; }
.nav-mobile-close { display: none; background: none; border: none; color: #94a3b8; cursor: pointer; padding: 8px; position: absolute; top: 12px; right: 16px; }

@media (max-width: 1024px) {
  .nav-links {
    position: fixed; top: 0; right: -280px; width: 280px; height: 100vh;
    background: #0f172a; flex-direction: column; padding: 60px 20px 20px;
    gap: 4px; transition: right 0.3s ease; z-index: 1001;
    box-shadow: -4px 0 20px rgba(0,0,0,0.3);
  }
  .nav-links.open { right: 0; }
  .nav-links a { width: 100%; padding: 12px 16px; }
  .nav-mobile-toggle { display: block; }
  .nav-mobile-close { display: block; }
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 600px;
  height: calc(100vh - 64px);
  max-height: 900px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.hero-bg {
  position: absolute; inset: 0;
  background: url('../images/hero-bg.jpg') center/cover no-repeat;
}
.hero-overlay {
  position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(15,23,42,0.7) 0%, rgba(15,23,42,0.5) 50%, rgba(15,23,42,0.75) 100%);
}
.hero-content {
  position: relative; z-index: 2;
  text-align: center;
  color: #fff;
  max-width: 800px;
  padding: 0 24px;
}
.hero-title {
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: 2px;
  line-height: 1.3;
  text-shadow: 0 2px 20px rgba(0,0,0,0.3);
}
.hero-en {
  font-size: 1rem;
  color: rgba(255,255,255,0.75);
  margin-top: 12px;
  letter-spacing: 1px;
  font-weight: 400;
}
.hero-gradient-line {
  width: 80px;
  height: 4px;
  background: linear-gradient(90deg, #6366f1, #f97316);
  margin: 20px auto;
  border-radius: 2px;
}
.hero-desc {
  font-size: 1.05rem;
  color: rgba(255,255,255,0.8);
  margin: 20px 0 32px;
  line-height: 1.8;
}
.hero-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-bottom: 36px;
}
.hero-tag {
  padding: 6px 16px;
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 20px;
  font-size: 0.8rem;
  color: rgba(255,255,255,0.85);
  backdrop-filter: blur(4px);
}
@media (max-width: 768px) {
  .hero { min-height: 500px; height: auto; padding: 80px 0; }
  .hero-title { font-size: 1.8rem; }
  .hero-en { font-size: 0.85rem; }
  .hero-desc { font-size: 0.9rem; }
}

/* ===== Section Spacing ===== */
.section { padding: 80px 0; }
.section-light { background: #f8fafc; }
.section-header { margin-bottom: 48px; }

/* ===== Intro Section ===== */
.intro-text {
  max-width: 800px;
  margin: 0 auto;
  font-size: 1.05rem;
  color: #475569;
  line-height: 2;
  text-align: center;
}
.intro-text p { margin-bottom: 16px; }

/* ===== Research Cards ===== */
.research-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.research-card {
  background: #fff;
  border-radius: 12px;
  padding: 32px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  border: 1px solid #f1f5f9;
  transition: all 0.3s ease;
}
.research-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(0,0,0,0.08);
}
.research-icon {
  width: 56px; height: 56px;
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem; margin-bottom: 20px;
}
.research-icon.indigo { background: #eef2ff; color: #6366f1; }
.research-icon.orange { background: #fff7ed; color: #f97316; }
.research-icon.slate { background: #f8fafc; color: #475569; }
.research-card h3 { font-size: 1.15rem; font-weight: 600; color: #0f172a; margin-bottom: 10px; }
.research-card p { font-size: 0.9rem; color: #64748b; line-height: 1.7; }
@media (max-width: 768px) {
  .research-grid { grid-template-columns: 1fr; }
}

/* ===== Achievement Cards ===== */
.achievement-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.achievement-card {
  background: #fff;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  border: 1px solid #f1f5f9;
  transition: all 0.3s ease;
}
.achievement-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(0,0,0,0.08);
}
.achievement-year {
  height: 140px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  font-weight: 800;
  color: #fff;
}
.achievement-year.y2025a { background: linear-gradient(135deg, #6366f1, #a855f7); }
.achievement-year.y2025b { background: linear-gradient(135deg, #f97316, #f43f5e); }
.achievement-year.y2024 { background: linear-gradient(135deg, #0ea5e9, #6366f1); }
.achievement-card-body { padding: 24px; }
.achievement-card-body h3 { font-size: 1.05rem; font-weight: 600; color: #0f172a; margin-bottom: 8px; line-height: 1.5; }
.achievement-card-body .journal { font-size: 0.8rem; color: #94a3b8; margin-bottom: 12px; }
.achievement-card-body a { font-size: 0.85rem; color: #6366f1; font-weight: 500; display: inline-flex; align-items: center; gap: 4px; }
.achievement-card-body a:hover { color: #4f46e5; }
@media (max-width: 768px) {
  .achievement-grid { grid-template-columns: 1fr; }
}

/* ===== News List ===== */
.news-list { max-width: 900px; margin: 0 auto; }
.news-item {
  display: flex;
  gap: 20px;
  padding: 24px 0;
  border-bottom: 1px solid #f1f5f9;
  transition: all 0.25s ease;
}
.news-item:hover { padding-left: 8px; }
.news-date {
  width: 60px;
  flex-shrink: 0;
  text-align: center;
}
.news-date .day { font-size: 1.6rem; font-weight: 700; color: #f97316; line-height: 1; }
.news-date .month { font-size: 0.75rem; color: #94a3b8; }
.news-content h3 { font-size: 1.05rem; font-weight: 600; color: #0f172a; margin-bottom: 6px; }
.news-content p { font-size: 0.85rem; color: #64748b; line-height: 1.7; }
.news-tag {
  display: inline-block;
  padding: 2px 10px;
  background: #eef2ff;
  color: #6366f1;
  border-radius: 4px;
  font-size: 0.7rem;
  margin-top: 8px;
}
@media (max-width: 640px) {
  .news-item { flex-direction: column; gap: 8px; }
  .news-date { display: flex; align-items: center; gap: 6px; width: auto; }
  .news-date .day { font-size: 1rem; }
}

/* ===== Team ===== */
.team-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 20px;
}
.team-card {
  background: #fff;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  border: 1px solid #f1f5f9;
  text-align: center;
  transition: all 0.3s ease;
}
.team-card:hover { transform: translateY(-4px); box-shadow: 0 12px 40px rgba(0,0,0,0.08); }
.team-card-photo {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
  background: linear-gradient(135deg, #e2e8f0, #f1f5f9);
}
.team-card-body { padding: 20px 16px; }
.team-card-body h3 { font-size: 1rem; font-weight: 600; color: #0f172a; margin-bottom: 4px; }
.team-card-body .role { font-size: 0.8rem; color: #f97316; font-weight: 500; margin-bottom: 6px; }
.team-card-body .field { font-size: 0.8rem; color: #64748b; line-height: 1.5; }
@media (max-width: 1024px) { .team-grid { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 768px) { .team-grid { grid-template-columns: repeat(2, 1fr); gap: 16px; } }

/* ===== About Page ===== */
.about-content { max-width: 900px; margin: 0 auto; }
.about-content h3 { font-size: 1.3rem; font-weight: 600; color: #0f172a; margin: 32px 0 16px; }
.about-content p { font-size: 1rem; color: #475569; line-height: 2; margin-bottom: 12px; }
.about-content ul { margin: 12px 0 12px 24px; color: #475569; }
.about-content li { margin-bottom: 8px; line-height: 1.8; }
.about-mission {
  background: linear-gradient(135deg, #eef2ff, #fff7ed);
  border-radius: 12px;
  padding: 32px;
  margin-top: 32px;
  border-left: 4px solid #6366f1;
}
.about-mission h4 { font-size: 1.1rem; font-weight: 600; color: #0f172a; margin-bottom: 12px; }
.about-mission p { font-size: 0.95rem; color: #475569; line-height: 1.8; }

/* ===== Research Detail Page ===== */
.research-detail-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: start;
}
.research-detail-item {
  background: #fff;
  border-radius: 12px;
  padding: 32px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  border: 1px solid #f1f5f9;
}
.research-detail-item h3 { font-size: 1.2rem; font-weight: 600; color: #0f172a; margin-bottom: 12px; display: flex; align-items: center; gap: 10px; }
.research-detail-item p { font-size: 0.95rem; color: #475569; line-height: 1.9; }
.research-detail-item ul { margin: 12px 0 0 20px; color: #475569; font-size: 0.9rem; }
.research-detail-item li { margin-bottom: 6px; }
@media (max-width: 768px) { .research-detail-grid { grid-template-columns: 1fr; } }

/* ===== Achievements Page ===== */
.achieve-filter { display: flex; justify-content: center; gap: 8px; margin-bottom: 32px; flex-wrap: wrap; }
.achieve-filter button { padding: 8px 20px; border: 1px solid #e2e8f0; background: #fff; border-radius: 6px; cursor: pointer; font-size: 0.85rem; color: #475569; transition: all 0.2s; }
.achieve-filter button:hover, .achieve-filter button.active { background: #0f172a; color: #fff; border-color: #0f172a; }
.achieve-list { max-width: 900px; margin: 0 auto; }
.achieve-item { padding: 28px 0; border-bottom: 1px solid #f1f5f9; display: flex; gap: 20px; align-items: flex-start; }
.achieve-item:last-child { border-bottom: none; }
.achieve-year-badge { flex-shrink: 0; width: 64px; height: 64px; border-radius: 12px; display: flex; align-items: center; justify-content: center; font-weight: 700; color: #fff; font-size: 0.85rem; }
.achieve-year-badge.y2025 { background: linear-gradient(135deg, #6366f1, #a855f7); }
.achieve-year-badge.y2024 { background: linear-gradient(135deg, #f97316, #f43f5e); }
.achieve-year-badge.y2023 { background: linear-gradient(135deg, #0ea5e9, #6366f1); }
.achieve-item h3 { font-size: 1.1rem; font-weight: 600; color: #0f172a; margin-bottom: 6px; }
.achieve-item .journal { font-size: 0.8rem; color: #64748b; margin-bottom: 8px; }
.achieve-item .authors { font-size: 0.8rem; color: #94a3b8; }
@media (max-width: 640px) { .achieve-item { flex-direction: column; gap: 12px; } }

/* ===== Admissions Page ===== */
.admission-cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.admission-card {
  background: #fff;
  border-radius: 12px;
  padding: 32px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  border: 1px solid #f1f5f9;
}
.admission-card h3 { font-size: 1.15rem; font-weight: 600; color: #0f172a; margin-bottom: 12px; }
.admission-card ul { margin-left: 20px; color: #475569; font-size: 0.9rem; }
.admission-card li { margin-bottom: 8px; line-height: 1.7; }
.admission-highlight {
  background: linear-gradient(135deg, #eef2ff, #fff7ed);
  border-radius: 12px;
  padding: 32px;
  margin-top: 32px;
  text-align: center;
}
.admission-highlight h3 { font-size: 1.2rem; font-weight: 600; color: #0f172a; margin-bottom: 12px; }
.admission-highlight p { color: #475569; line-height: 1.8; }
@media (max-width: 768px) { .admission-cards { grid-template-columns: 1fr; } }

/* ===== Contact Page ===== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.contact-info h3 { font-size: 1.2rem; font-weight: 600; color: #0f172a; margin-bottom: 20px; }
.contact-item { display: flex; gap: 16px; margin-bottom: 24px; align-items: flex-start; }
.contact-icon { width: 44px; height: 44px; border-radius: 10px; background: #eef2ff; color: #6366f1; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.contact-item h4 { font-size: 0.95rem; font-weight: 600; color: #0f172a; margin-bottom: 4px; }
.contact-item p { font-size: 0.85rem; color: #64748b; line-height: 1.6; }
.contact-map {
  background: linear-gradient(135deg, #e2e8f0, #f1f5f9);
  border-radius: 12px;
  min-height: 360px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #94a3b8;
  font-size: 0.9rem;
  border: 1px solid #f1f5f9;
}
@media (max-width: 768px) { .contact-grid { grid-template-columns: 1fr; } }

/* ===== Footer ===== */
.footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 56px 0 24px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}
.footer-logo { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; }
.footer-logo-icon {
  width: 32px; height: 32px;
  background: linear-gradient(135deg, #6366f1, #f97316);
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 700; font-size: 0.75rem;
}
.footer-logo-text { color: #fff; font-weight: 600; font-size: 1rem; }
.footer-slogan { color: #64748b; font-size: 0.85rem; margin-top: 8px; }
.footer h4 { color: #fff; font-size: 0.95rem; font-weight: 600; margin-bottom: 16px; }
.footer-links { list-style: none; }
.footer-links li { margin-bottom: 10px; }
.footer-links a { color: #94a3b8; font-size: 0.85rem; transition: color 0.2s; }
.footer-links a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  padding-top: 20px;
  text-align: center;
  font-size: 0.8rem;
  color: #475569;
}
@media (max-width: 768px) {
  .footer-grid { grid-template-columns: 1fr; gap: 32px; }
}

/* ===== Breadcrumb ===== */
.breadcrumb { background: #f8fafc; padding: 16px 0; border-bottom: 1px solid #f1f5f9; }
.breadcrumb-inner { max-width: 1200px; margin: 0 auto; padding: 0 24px; font-size: 0.8rem; color: #64748b; }
.breadcrumb-inner a { color: #475569; }
.breadcrumb-inner a:hover { color: #f97316; }
.breadcrumb-inner span { color: #94a3b8; margin: 0 6px; }

/* ===== Animations ===== */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}
.fade-in-up { animation: fadeInUp 0.6s ease-out both; }
.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }

/* ===== Scroll Reveal ===== */
.reveal { opacity: 0; transform: translateY(30px); transition: all 0.6s ease-out; }
.reveal.visible { opacity: 1; transform: translateY(0); }

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 44px;
  height: 44px;
  background: #0f172a;
  color: #fff;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 999;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}
.back-to-top.visible { opacity: 1; visibility: visible; }
.back-to-top:hover { background: #f97316; transform: translateY(-2px); }