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

:root {
  --primary: #1a3a5c;
  --primary-light: #2a5a8c;
  --primary-dark: #0e1f33;
  --accent: #e67e22;
  --accent-light: #f39c12;
  --bg: #f4f7fb;
  --card-bg: #ffffff;
  --text: #2c3e50;
  --text-light: #7f8c8d;
  --radius: 16px;
  --shadow: 0 8px 32px rgba(0,0,0,0.08);
  --glass: rgba(255,255,255,0.7);
  --transition: 0.3s ease;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

/* 暗色模式变量 */
body.dark {
  --bg: #0e1f33;
  --card-bg: #1a2d44;
  --text: #ecf0f1;
  --text-light: #bdc3c7;
  --glass: rgba(26,45,68,0.8);
  --shadow: 0 8px 32px rgba(0,0,0,0.3);
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.8;
  transition: background var(--transition), color var(--transition);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

ul { list-style: none; }

/* ===== 容器 ===== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ===== 通用区块 ===== */
.section { padding: 80px 0; }

.section-title {
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 16px;
  text-align: center;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section-subtitle {
  text-align: center;
  color: var(--text-light);
  font-size: 1.1rem;
  margin-bottom: 48px;
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
}

/* ===== 网格系统 ===== */
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

/* ===== 卡片 ===== */
.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
  border: 1px solid rgba(255,255,255,0.1);
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: 0 16px 48px rgba(0,0,0,0.12);
}

.glass-card {
  background: var(--glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
}

/* ===== 按钮 ===== */
.btn {
  display: inline-block;
  padding: 14px 36px;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  color: #fff;
  border-radius: 50px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition);
  text-decoration: none;
  font-size: 1rem;
}

.btn:hover {
  transform: scale(1.05);
  box-shadow: 0 8px 24px rgba(26,58,92,0.4);
}

.btn-accent {
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
}

/* ===== 滚动动画 ===== */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== 暗色模式切换按钮 ===== */
.dark-toggle {
  position: fixed;
  bottom: 30px;
  right: 30px;
  z-index: 999;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  border: none;
  font-size: 24px;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(0,0,0,0.2);
  transition: transform var(--transition);
}

.dark-toggle:hover {
  transform: scale(1.1);
}

/* ===== 返回顶部按钮 ===== */
.back-to-top {
  position: fixed;
  bottom: 100px;
  right: 30px;
  z-index: 998;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  border: none;
  font-size: 20px;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(0,0,0,0.2);
  display: none;
  transition: transform var(--transition);
}

.back-to-top:hover {
  transform: scale(1.1);
}

/* ===== Header ===== */
header {
  background: rgba(26,58,92,0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  color: #fff;
  padding: 20px 0;
  position: sticky;
  top: 0;
  z-index: 1000;
}

header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

header .logo {
  font-size: 1.8rem;
  font-weight: 800;
  letter-spacing: 2px;
}

#mainNav {
  display: flex;
  gap: 28px;
}

#mainNav a {
  color: #fff;
  font-weight: 500;
  transition: color var(--transition);
}

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

.header-actions {
  display: flex;
  gap: 16px;
  align-items: center;
}

.search-wrapper {
  position: relative;
}

#searchInput {
  padding: 10px 16px;
  border-radius: 50px;
  border: none;
  background: rgba(255,255,255,0.2);
  color: #fff;
  width: 200px;
  outline: none;
  transition: background var(--transition);
}

#searchInput::placeholder {
  color: rgba(255,255,255,0.6);
}

#searchInput:focus {
  background: rgba(255,255,255,0.3);
}

#searchBtn {
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  color: #fff;
  cursor: pointer;
  font-size: 1rem;
}

#mobileMenuBtn {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 28px;
  cursor: pointer;
}

/* ===== Hero / Banner ===== */
#home {
  background: linear-gradient(135deg, var(--primary) 0%, #0e1f33 50%, var(--primary-light) 100%);
  color: #fff;
  padding: 120px 0 80px;
  position: relative;
  overflow: hidden;
}

#home::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -20%;
  width: 80%;
  height: 200%;
  background: radial-gradient(circle, rgba(230,126,34,0.15) 0%, transparent 70%);
  pointer-events: none;
}

#home .container {
  position: relative;
  z-index: 1;
}

.hero-content {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
}

.hero-content h1 {
  font-size: 3.5rem;
  font-weight: 900;
  margin-bottom: 24px;
  line-height: 1.2;
}

.hero-content h1 span {
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-content p {
  font-size: 1.3rem;
  opacity: 0.9;
  margin-bottom: 40px;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 20px;
  justify-content: center;
  flex-wrap: wrap;
}

.hero-buttons .btn-outline {
  background: rgba(255,255,255,0.2);
  color: #fff;
  border: 2px solid rgba(255,255,255,0.3);
}

.hero-buttons .btn-outline:hover {
  background: rgba(255,255,255,0.3);
  border-color: rgba(255,255,255,0.5);
}

/* ===== 面包屑 ===== */
#breadcrumb {
  background: var(--card-bg);
  padding: 16px 0;
  border-bottom: 1px solid rgba(0,0,0,0.05);
}

#breadcrumb nav {
  font-size: 0.9rem;
  color: var(--text-light);
}

#breadcrumb a {
  color: var(--text-light);
}

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

#breadcrumb span {
  color: var(--text);
}

/* ===== About 区块 ===== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.about-text p {
  font-size: 1.1rem;
  margin-bottom: 20px;
}

.about-visual {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 40px;
  box-shadow: var(--shadow);
}

/* ===== 统计数字 ===== */
#stats {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff;
}

.stat-number {
  font-size: 3rem;
  font-weight: 900;
}

/* ===== FAQ ===== */
.faq-item {
  border-bottom: 1px solid rgba(0,0,0,0.1);
  padding: 20px 0;
}

.faq-question {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text);
  padding: 0;
}

.faq-question:hover {
  color: var(--accent);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.faq-answer p {
  padding-top: 12px;
  color: var(--text-light);
}

/* ===== HowTo 步骤 ===== */
.step-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.step-number {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 12px;
  font-size: 1.5rem;
  font-weight: bold;
  color: #fff;
}

/* ===== Contact 表单 ===== */
.contact-info h3 {
  font-size: 1.2rem;
  margin-bottom: 8px;
}

.contact-info p {
  color: var(--text-light);
  margin-bottom: 24px;
}

.contact-map {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
}

/* ===== Footer ===== */
footer {
  background: var(--primary);
  color: #fff;
  padding: 48px 0 24px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 32px;
}

footer h3 {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 12px;
}

footer h4 {
  font-size: 1.1rem;
  margin-bottom: 12px;
}

footer p, footer li {
  opacity: 0.8;
  margin-bottom: 8px;
}

footer a {
  color: #fff;
}

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

.footer-bottom {
  text-align: center;
  padding-top: 24px;
  border-top: 1px solid rgba(255,255,255,0.1);
  opacity: 0.7;
  font-size: 0.9rem;
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .step-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .grid-3 {
    grid-template-columns: 1fr;
  }
  .grid-4 {
    grid-template-columns: 1fr;
  }
  .section {
    padding: 48px 0;
  }
  .section-title {
    font-size: 1.8rem;
  }
  .about-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }
  .step-grid {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .hero-content h1 {
    font-size: 2.2rem;
  }
  .hero-content p {
    font-size: 1.1rem;
  }
  #mainNav {
    display: none;
  }
  #mobileMenuBtn {
    display: block;
  }
  #searchInput {
    width: 140px;
  }
}

/* ===== 移动端导航展开 ===== */
@media (max-width: 768px) {
  #mainNav.mobile-open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 70px;
    right: 20px;
    background: var(--primary);
    padding: 20px;
    border-radius: 12px;
    gap: 16px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.3);
    min-width: 200px;
  }
}

/* ===== 图片懒加载 ===== */
svg[loading="lazy"] {
  opacity: 0;
  transition: opacity 0.5s ease;
}

/* ===== 友情链接 ===== */
.friend-links {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  justify-content: center;
}

.friend-links a {
  color: var(--text-light);
  transition: color var(--transition);
}

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

/* ===== 其他辅助类 ===== */
.text-center { text-align: center; }
.mb-12 { margin-bottom: 12px; }
.mb-16 { margin-bottom: 16px; }
.mb-20 { margin-bottom: 20px; }
.mb-24 { margin-bottom: 24px; }
.mb-32 { margin-bottom: 32px; }
.mb-48 { margin-bottom: 48px; }