/* ===== 全局重置与基础 ===== */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #1b3a5c;
  --primary-light: #2a5a8c;
  --accent: #f0c040;
  --accent-hover: #d4a830;
  --bg: #f4f7fc;
  --bg-card: rgba(255, 255, 255, 0.75);
  --bg-glass: rgba(255, 255, 255, 0.25);
  --text: #1a1a2e;
  --text-light: #555;
  --text-inverse: #fff;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.08);
  --shadow-hover: 0 16px 48px rgba(0, 0, 0, 0.14);
  --radius: 20px;
  --radius-sm: 12px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --nav-bg: rgba(27, 58, 92, 0.85);
  --footer-bg: #0b1a2e;
  --border-glass: 1px solid rgba(255, 255, 255, 0.3);
}

[data-theme="dark"] {
  --bg: #0d1b2a;
  --bg-card: rgba(27, 58, 92, 0.6);
  --bg-glass: rgba(27, 58, 92, 0.3);
  --text: #e0e6ed;
  --text-light: #aab;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
  --shadow-hover: 0 16px 48px rgba(0, 0, 0, 0.6);
  --nav-bg: rgba(11, 26, 46, 0.9);
  --footer-bg: #050f1a;
  --border-glass: 1px solid rgba(255, 255, 255, 0.08);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  transition: background var(--transition), color var(--transition);
  overflow-x: hidden;
}

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

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

ul, ol {
  list-style: none;
  padding-left: 0;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font: inherit;
  color: inherit;
}

/* ===== 渐变动画背景 ===== */
@keyframes gradientShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

/* ===== 滚动动画 (Intersection Observer) ===== */
.fade-in-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.fade-in-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== 导航栏 ===== */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  background: var(--nav-bg);
  border-bottom: var(--border-glass);
  transition: background var(--transition), border var(--transition);
}

nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.6rem 1.5rem;
  gap: 1rem;
}

.logo-link svg {
  height: 36px;
  width: auto;
  transition: transform var(--transition);
}
.logo-link:hover svg {
  transform: scale(1.03);
}

nav ul {
  display: flex;
  gap: 1.8rem;
  align-items: center;
}

nav ul li a {
  color: var(--text-inverse);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 0.4rem 0;
  position: relative;
  transition: color var(--transition);
}
nav ul li a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width var(--transition);
}
nav ul li a:hover::after,
nav ul li a[aria-current="page"]::after {
  width: 100%;
}
nav ul li a:hover {
  color: var(--accent);
}

#darkModeToggle,
#mobileMenuToggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: rgba(255,255,255,0.1);
  color: var(--text-inverse);
  transition: background var(--transition), transform var(--transition);
}
#darkModeToggle:hover,
#mobileMenuToggle:hover {
  background: rgba(255,255,255,0.2);
  transform: scale(1.05);
}

#mobileMenuToggle {
  display: none;
}

/* ===== Hero 横幅 ===== */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 6rem 2rem 4rem;
  background: linear-gradient(135deg, #0b1a2e 0%, #1b3a5c 30%, #2a5a8c 60%, #1b3a5c 100%);
  background-size: 200% 200%;
  animation: gradientShift 12s ease infinite;
  position: relative;
  overflow: hidden;
}

#hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 30% 50%, rgba(240,192,64,0.08) 0%, transparent 60%);
  pointer-events: none;
}

#hero > div {
  position: relative;
  z-index: 1;
  max-width: 800px;
}

#hero h1 {
  font-size: clamp(2.2rem, 6vw, 3.8rem);
  font-weight: 800;
  color: #fff;
  text-shadow: 0 4px 20px rgba(0,0,0,0.3);
  margin-bottom: 1rem;
  line-height: 1.2;
}

#hero p {
  font-size: clamp(1rem, 2.5vw, 1.3rem);
  color: rgba(255,255,255,0.85);
  margin-bottom: 2.2rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

#hero a[role="button"] {
  display: inline-block;
  padding: 0.9rem 2.5rem;
  border-radius: 50px;
  font-weight: 600;
  font-size: 1.05rem;
  background: var(--accent);
  color: #0b1a2e;
  margin: 0.5rem;
  transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
  box-shadow: 0 8px 24px rgba(240,192,64,0.3);
}
#hero a[role="button"]:hover {
  transform: translateY(-4px) scale(1.02);
  box-shadow: 0 12px 36px rgba(240,192,64,0.45);
  background: var(--accent-hover);
}

#hero a[role="button"]:last-child {
  background: rgba(255,255,255,0.15);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(255,255,255,0.25);
  color: #fff;
  box-shadow: none;
}
#hero a[role="button"]:last-child:hover {
  background: rgba(255,255,255,0.25);
  border-color: var(--accent);
  color: var(--accent);
}

/* ===== 通用 section ===== */
main section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 5rem 2rem;
}

main section h2 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 700;
  margin-bottom: 2rem;
  text-align: center;
  position: relative;
  display: inline-block;
  left: 50%;
  transform: translateX(-50%);
}
main section h2::after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background: var(--accent);
  border-radius: 4px;
  margin: 0.8rem auto 0;
}

/* ===== 卡片通用 ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 2rem;
}

.card {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: var(--radius);
  padding: 2rem 1.5rem;
  box-shadow: var(--shadow);
  border: var(--border-glass);
  transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
  cursor: default;
}
.card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-hover);
  background: rgba(255,255,255,0.85);
}
[data-theme="dark"] .card:hover {
  background: rgba(27,58,92,0.75);
}

.card h3 {
  font-size: 1.3rem;
  font-weight: 600;
  margin-bottom: 0.8rem;
  color: var(--primary);
}
[data-theme="dark"] .card h3 {
  color: var(--accent);
}

.card p {
  color: var(--text-light);
  font-size: 0.95rem;
}

/* ===== About ===== */
#about p {
  max-width: 800px;
  margin: 1rem auto;
  text-align: center;
  color: var(--text-light);
  line-height: 1.9;
}

/* ===== Products & Solutions ===== */
#products > div,
#solutions > div {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 2rem;
}

#products article,
#solutions article {
  composes: card;
}

/* ===== Features ===== */
#features ul {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  max-width: 1000px;
  margin: 0 auto;
}

#features ul li {
  background: var(--bg-card);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: var(--radius-sm);
  padding: 1.5rem 1.8rem;
  box-shadow: var(--shadow);
  border: var(--border-glass);
  transition: transform var(--transition), box-shadow var(--transition);
  font-size: 0.95rem;
  color: var(--text-light);
}
#features ul li:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}
#features ul li strong {
  color: var(--primary);
  display: block;
  font-size: 1.05rem;
  margin-bottom: 0.3rem;
}
[data-theme="dark"] #features ul li strong {
  color: var(--accent);
}

/* ===== Knowledge Hub ===== */
#knowledge-hub > div {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 2rem;
}

#knowledge-hub article {
  composes: card;
}

#knowledge-hub article a {
  display: inline-block;
  margin-top: 0.8rem;
  font-weight: 500;
  color: var(--primary-light);
  transition: color var(--transition);
}
#knowledge-hub article a:hover {
  color: var(--accent);
}

/* ===== HowTo ===== */
#howto {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border: var(--border-glass);
  max-width: 800px;
  margin: 0 auto 2rem;
  padding: 3rem 2.5rem;
}

#howto h2 {
  margin-bottom: 1rem;
}

#howto p {
  text-align: center;
  color: var(--text-light);
  margin-bottom: 1.5rem;
}

#howto ol {
  counter-reset: step;
  padding-left: 0;
}

#howto ol li {
  counter-increment: step;
  padding: 1rem 1rem 1rem 3rem;
  position: relative;
  border-bottom: 1px solid rgba(0,0,0,0.05);
  color: var(--text);
  font-size: 0.98rem;
}
[data-theme="dark"] #howto ol li {
  border-bottom-color: rgba(255,255,255,0.06);
}

#howto ol li::before {
  content: counter(step);
  position: absolute;
  left: 0.5rem;
  top: 1rem;
  width: 32px;
  height: 32px;
  background: var(--accent);
  color: #0b1a2e;
  font-weight: 700;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
}

#howto ol li:last-child {
  border-bottom: none;
}

/* ===== FAQ ===== */
#faq > div {
  max-width: 800px;
  margin: 0 auto;
}

details {
  background: var(--bg-card);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: var(--radius-sm);
  margin-bottom: 1rem;
  box-shadow: var(--shadow);
  border: var(--border-glass);
  overflow: hidden;
  transition: box-shadow var(--transition);
}
details:hover {
  box-shadow: var(--shadow-hover);
}

details summary {
  padding: 1.2rem 1.5rem;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  position: relative;
  list-style: none;
  color: var(--text);
  transition: color var(--transition);
}
details summary::-webkit-details-marker {
  display: none;
}
details summary::after {
  content: '+';
  position: absolute;
  right: 1.5rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.5rem;
  font-weight: 300;
  color: var(--primary-light);
  transition: transform var(--transition), color var(--transition);
}
details[open] summary::after {
  content: '−';
  transform: translateY(-50%) rotate(0deg);
  color: var(--accent);
}

details p {
  padding: 0 1.5rem 1.2rem;
  color: var(--text-light);
  font-size: 0.95rem;
  line-height: 1.8;
}

/* ===== Contact ===== */
#contact address {
  max-width: 500px;
  margin: 1.5rem auto 0;
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  border: var(--border-glass);
  font-style: normal;
  display: grid;
  gap: 1rem;
}

#contact address p {
  font-size: 0.98rem;
  color: var(--text);
}
#contact address a {
  color: var(--primary-light);
  font-weight: 500;
}
#contact address a:hover {
  color: var(--accent);
}

/* ===== Footer ===== */
footer {
  background: var(--footer-bg);
  color: rgba(255,255,255,0.7);
  padding: 2.5rem 2rem;
  text-align: center;
  font-size: 0.9rem;
  border-top: 1px solid rgba(255,255,255,0.05);
}

footer > div {
  max-width: 1200px;
  margin: 0 auto;
}

footer p {
  margin-bottom: 0.8rem;
}

footer nav ul {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin: 1rem 0;
}

footer nav ul li a {
  color: rgba(255,255,255,0.6);
  transition: color var(--transition);
}
footer nav ul li a:hover {
  color: var(--accent);
}

/* ===== 返回顶部 ===== */
#backToTop {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 20px rgba(0,0,0,0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: opacity var(--transition), transform var(--transition), visibility var(--transition), background var(--transition);
  z-index: 999;
}
#backToTop.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
#backToTop:hover {
  background: var(--accent);
  color: #0b1a2e;
  transform: translateY(-4px);
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  nav ul {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: var(--nav-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    padding: 1.5rem 2rem;
    gap: 1rem;
    border-bottom: var(--border-glass);
  }
  nav ul.open {
    display: flex;
  }

  #mobileMenuToggle {
    display: flex;
  }

  #hero {
    padding: 5rem 1.5rem 3rem;
  }
  #hero a[role="button"] {
    display: block;
    width: 80%;
    margin: 0.6rem auto;
  }

  main section {
    padding: 3rem 1.2rem;
  }

  .card-grid,
  #products > div,
  #solutions > div,
  #knowledge-hub > div {
    grid-template-columns: 1fr;
  }

  #features ul {
    grid-template-columns: 1fr;
  }

  #howto {
    padding: 2rem 1.2rem;
  }

  details summary {
    padding: 1rem 1.2rem;
  }

  #backToTop {
    bottom: 1.2rem;
    right: 1.2rem;
    width: 42px;
    height: 42px;
  }
}

@media (max-width: 480px) {
  html {
    font-size: 15px;
  }

  nav {
    padding: 0.5rem 1rem;
  }

  #hero h1 {
    font-size: 1.9rem;
  }
  #hero p {
    font-size: 0.95rem;
  }

  footer nav ul {
    flex-direction: column;
    gap: 0.8rem;
  }
}