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

:root {
  --color-primary: #FF4D2E;
  --color-primary-dark: #B32D2E;
  --color-secondary: #0B3B8C;
  --color-secondary-light: #00A8FF;
  --color-bg-warm: #F8F4EC;
  --color-ink: #1C1C2A;
  --color-accent-orange: #FF7A45;
  --color-accent-cyan: #00A8FF;
  --color-border: #E5E1D9;
  --color-white: #FFFFFF;
  --color-dark-bg: #1C1C2A;
  --color-dark-text: #F8F4EC;
  --font-head: "Rajdhani", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  --font-num: "Bahnschrift", "DIN Pro", "Roboto Mono", monospace;
  --shadow-sm: 0 2px 8px rgba(28, 28, 42, 0.08);
  --shadow-md: 4px 4px 0 rgba(28, 28, 42, 0.12);
  --shadow-lg: 8px 8px 0 rgba(28, 28, 42, 0.14);
  --radius: 2px;
  --container-max: 1280px;
  --header-h: 84px;
  --transition: 0.3s ease;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-ink);
  background-color: var(--color-bg-warm);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

img { max-width: 100%; display: block; height: auto; }
a { color: var(--color-secondary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-primary); }
ul, ol { list-style: none; }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-head);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-ink);
}

:focus-visible {
  outline: 3px solid var(--color-accent-cyan);
  outline-offset: 2px;
}

::selection { background: var(--color-primary); color: var(--color-white); }

/* ===== 通用布局 ===== */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding-left: 24px;
  padding-right: 24px;
  width: 100%;
}

.main-content {
  min-height: calc(100vh - var(--header-h) - 320px);
  padding-top: var(--header-h);
}

.skip-link {
  position: fixed;
  top: -100px;
  left: 16px;
  z-index: 10000;
  background: var(--color-ink);
  color: var(--color-white);
  padding: 12px 20px;
  font-weight: bold;
  border-radius: var(--radius);
  text-decoration: none;
  transition: top 0.3s;
}

.skip-link:focus-visible { top: 16px; }

/* ===== 头部 ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--color-white);
  border-bottom: 4px solid var(--color-ink);
  box-shadow: 0 4px 0 rgba(28, 28, 42, 0.08);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: var(--header-h);
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  flex-shrink: 0;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  background: var(--color-primary);
  color: var(--color-white);
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 22px;
  letter-spacing: 1px;
  transform: skew(-8deg);
  border: 3px solid var(--color-ink);
  box-shadow: 3px 3px 0 var(--color-ink);
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-text strong {
  font-family: var(--font-head);
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.5px;
  color: var(--color-ink);
  text-transform: uppercase;
}

.brand-text small {
  font-size: 12px;
  color: #6b6b7a;
}

.nav-desktop {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-desktop a {
  position: relative;
  display: inline-block;
  padding: 10px 14px;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 16px;
  letter-spacing: 0.5px;
  color: var(--color-ink);
  text-decoration: none;
  border: 2px solid transparent;
  transition: all 0.3s;
}

.nav-desktop a::after {
  content: "";
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 4px;
  height: 3px;
  background: var(--color-primary);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s;
}

.nav-desktop a:hover {
  color: var(--color-primary);
}

.nav-desktop a:hover::after,
.nav-desktop a[aria-current="page"]::after {
  transform: scaleX(1);
}

.nav-desktop a[aria-current="page"] {
  color: var(--color-primary);
  border-color: var(--color-border);
}

.header-side {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 48px;
  height: 48px;
  padding: 12px;
  background: transparent;
  border: 2px solid var(--color-ink);
  cursor: pointer;
  border-radius: var(--radius);
}

.toggle-bar {
  display: block;
  width: 100%;
  height: 3px;
  background: var(--color-ink);
  transition: transform 0.3s, opacity 0.3s;
}

.nav-toggle[aria-expanded="true"] .toggle-bar:nth-child(1) { transform: translateY(8px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .toggle-bar:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .toggle-bar:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }

.mobile-nav {
  display: none;
  background: var(--color-ink);
  color: var(--color-white);
}

/* ===== 通用按钮 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 16px;
  letter-spacing: 0.5px;
  text-decoration: none;
  border: 2px solid var(--color-ink);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.3s;
  box-shadow: 3px 3px 0 rgba(28, 28, 42, 0.15);
}

.btn:hover { transform: translate(-1px, -1px); box-shadow: 4px 4px 0 rgba(28, 28, 42, 0.2); color: inherit; }

.btn-primary {
  background: var(--color-primary);
  color: var(--color-white);
  border-color: var(--color-ink);
}

.btn-primary:hover { background: var(--color-primary-dark); }

.btn-outline {
  background: transparent;
  color: var(--color-secondary);
  border-color: var(--color-secondary);
  box-shadow: 3px 3px 0 rgba(11, 59, 140, 0.15);
}

.btn-outline:hover { background: var(--color-secondary); color: var(--color-white); }

.btn-sm { padding: 8px 16px; font-size: 14px; }

/* ===== 页脚 ===== */
.site-footer {
  background: var(--color-dark-bg);
  color: var(--color-dark-text);
  border-top: 6px solid var(--color-primary);
  position: relative;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: -18px;
  right: 40px;
  width: 36px;
  height: 36px;
  background: var(--color-accent-orange);
  border: 4px solid var(--color-ink);
  transform: rotate(45deg);
  z-index: 1;
}

.footer-top {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 48px;
  padding-top: 64px;
  padding-bottom: 48px;
}

.footer-brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.footer-brand-logo .brand-mark {
  width: 48px;
  height: 48px;
  font-size: 18px;
}

.footer-brand-logo .brand-text strong { color: var(--color-dark-text); font-size: 18px; }
.footer-brand-logo .brand-text small { color: #a0a0b0; }

.footer-trust {
  font-size: 14px;
  color: #a0a0b0;
  line-height: 1.7;
  max-width: 320px;
  border-left: 3px solid var(--color-primary);
  padding-left: 14px;
}

.footer-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-white);
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 16px;
  position: relative;
  padding-bottom: 8px;
}

.footer-title::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 28px;
  height: 3px;
  background: var(--color-primary);
}

.footer-links li { margin-bottom: 8px; }

.footer-links a {
  color: #c0c0d0;
  font-size: 14px;
  padding: 2px 0;
  border-bottom: 1px solid transparent;
  transition: all 0.3s;
}

.footer-links a:hover { color: var(--color-white); border-bottom-color: var(--color-primary); }

.footer-contact li {
  color: #c0c0d0;
  font-size: 14px;
  margin-bottom: 10px;
  padding-left: 0;
  line-height: 1.6;
}

.footer-contact a { color: #c0c0d0; font-size: 14px; }
.footer-contact a:hover { color: var(--color-primary); }

.footer-note {
  font-size: 12px;
  color: #808090;
  margin-top: 12px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 12px;
}

.footer-bottom {
  background: #12121c;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.footer-bottom-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  padding-top: 20px;
  padding-bottom: 20px;
  font-size: 13px;
  color: #9090a0;
}

.footer-bottom-inner a { color: #9090a0; }
.footer-bottom-inner a:hover { color: var(--color-primary); }

/* ===== 面包屑 ===== */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  color: #808090;
  margin-bottom: 24px;
}

.breadcrumb a { color: var(--color-secondary); font-weight: 500; }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb span[aria-current="page"] { font-weight: 700; color: var(--color-ink); }
.breadcrumb li + li::before { content: "/"; margin-right: 6px; color: var(--color-border); }

/* ===== 章节头部 ===== */
.section-head {
  margin-bottom: 32px;
  max-width: 720px;
}

.section-tag {
  display: inline-block;
  font-family: var(--font-head);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--color-primary);
  background: rgba(255, 77, 46, 0.1);
  padding: 4px 10px;
  border-left: 3px solid var(--color-primary);
  margin-bottom: 10px;
  transform: skew(-6deg);
}

.section-title {
  font-size: 36px;
  font-family: var(--font-head);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-ink);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.section-desc {
  font-size: 16px;
  color: #6b6b7a;
  line-height: 1.7;
  margin-top: 12px;
}

/* ===== 卡片网格 ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}

.card {
  background: var(--color-white);
  border: 2px solid var(--color-ink);
  box-shadow: var(--shadow-md);
  border-radius: var(--radius);
  padding: 24px;
  transition: all 0.3s;
  position: relative;
}

.card:hover {
  transform: translate(-2px, -2px);
  box-shadow: var(--shadow-lg);
}

.card::before {
  content: "";
  position: absolute;
  top: -2px;
  left: -2px;
  width: 36px;
  height: 36px;
  background: var(--color-primary);
  clip-path: polygon(0 0, 100% 0, 0 100%);
  opacity: 0.6;
}

/* ===== 图片容器 ===== */
.image-frame {
  position: relative;
  background: var(--color-border);
  border: 2px solid var(--color-ink);
  border-radius: var(--radius);
  overflow: hidden;
  min-height: 240px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.image-frame::after {
  content: "";
  position: absolute;
  width: 80px;
  height: 80px;
  border: 4px solid rgba(28, 28, 42, 0.15);
  border-radius: 50%;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.image-frame-wide { aspect-ratio: 16 / 9; }
.image-frame-square { aspect-ratio: 1 / 1; }

.image-frame .image-caption {
  position: absolute;
  bottom: 0;
  left: 0;
  background: var(--color-ink);
  color: var(--color-white);
  font-size: 12px;
  padding: 4px 10px;
  font-family: var(--font-head);
  letter-spacing: 1px;
}

/* ===== 滚动进度条 ===== */
[data-progress] {
  position: fixed;
  top: 0;
  left: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--color-accent-orange), var(--color-primary), var(--color-secondary));
  z-index: 2000;
  width: 0%;
  transition: width 0.1s linear;
}

/* ===== 显现动画 ===== */
[data-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

[data-reveal][data-revealed] {
  opacity: 1;
  transform: translateY(0);
}

/* ===== 悬浮球 ===== */
.fab-menu {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 900;
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: flex-end;
}

.fab-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 16px;
  background: var(--color-ink);
  color: var(--color-white);
  font-family: var(--font-head);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  border: 2px solid var(--color-ink);
  border-radius: 24px;
  box-shadow: var(--shadow-md);
  transition: all 0.3s;
}

.fab-item:hover {
  background: var(--color-primary);
  color: var(--color-white);
  transform: translateY(-2px);
}

.fab-item::before {
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-accent-cyan);
  flex-shrink: 0;
}

/* ===== 数值强调 ===== */
.stat-number {
  font-family: var(--font-num);
  font-weight: 700;
  font-size: 1.4em;
  color: var(--color-primary);
}

/* ===== 响应式 ===== */
@media screen and (max-width: 1024px) {
  .nav-desktop { gap: 0; }
  .nav-desktop a { padding: 10px 10px; font-size: 15px; }
  .footer-top { grid-template-columns: 1fr 1fr; gap: 32px; }
}

@media screen and (max-width: 768px) {
  :root { --header-h: 72px; }

  .header-inner { min-height: var(--header-h); }

  .brand-logo .brand-mark { width: 42px; height: 42px; font-size: 18px; }
  .brand-text strong { font-size: 16px; }
  .brand-text small { display: none; }

  .nav-desktop { display: none; }

  .header-side .btn-outline { display: none; }

  .nav-toggle { display: flex; }

  .mobile-nav {
    display: block;
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--color-ink);
    background-image: linear-gradient(135deg, rgba(255, 77, 46, 0.08) 0%, transparent 40%, rgba(0, 168, 255, 0.08) 100%);
    z-index: 999;
    transform: translateX(100%);
    transition: transform 0.35s ease;
    overflow-y: auto;
    padding-top: 24px;
    padding-bottom: 80px;
  }

  .mobile-nav[data-open] { transform: translateX(0); }

  .mobile-nav-inner {
    max-width: 600px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    flex-direction: column;
  }

  .mobile-nav-inner > a {
    color: var(--color-white);
    font-family: var(--font-head);
    font-size: 26px;
    font-weight: 700;
    padding: 16px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.12);
    text-decoration: none;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: color 0.3s, padding-left 0.3s;
  }

  .mobile-nav-inner > a:hover {
    color: var(--color-accent-orange);
    padding-left: 8px;
  }

  .mobile-nav-inner > a[aria-current="page"] {
    color: var(--color-accent-cyan);
    border-left: 4px solid var(--color-primary);
    padding-left: 12px;
  }

  .mobile-nav-cta {
    margin-top: 32px;
    display: flex;
    flex-direction: column;
    gap: 14px;
  }

  .mobile-nav-cta .btn { width: 100%; }

  .mobile-nav-cta .btn-outline {
    color: var(--color-accent-cyan);
    border-color: var(--color-accent-cyan);
    box-shadow: 3px 3px 0 rgba(0, 168, 255, 0.2);
  }

  .mobile-nav-cta .btn-outline:hover { background: var(--color-accent-cyan); color: var(--color-white); }

  .footer-top { grid-template-columns: 1fr; gap: 32px; padding-top: 48px; }
  .footer-bottom-inner { flex-direction: column; text-align: center; }
  .section-title { font-size: 28px; }
  .card-grid { grid-template-columns: 1fr; }
  .fab-menu { right: 16px; bottom: 16px; }
  .fab-item span { display: none; }
  .fab-item { width: 48px; height: 48px; padding: 0; justify-content: center; border-radius: 50%; }
  .fab-item::before { width: 10px; height: 10px; }
  .main-content { padding-top: var(--header-h); }
}

@media screen and (max-width: 480px) {
  .container { padding-left: 16px; padding-right: 16px; }
  .brand-text strong { letter-spacing: 0; }
  .brand-mark { width: 38px; height: 38px; font-size: 16px; box-shadow: 2px 2px 0 var(--color-ink); }
  .section-title { font-size: 24px; }
  .section-tag { font-size: 12px; }
  .breadcrumb { font-size: 12px; }
}

/* ===== 无障碍 ===== */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; }
  [data-reveal] { opacity: 1; transform: none; }
  .mobile-nav { transition: none; }
}

/* 高对比度支持 */
@media (prefers-contrast: more) {
  :root {
    --color-primary: #CC2A00;
    --color-secondary: #00236E;
    --color-border: #000000;
  }
  .brand-mark { box-shadow: none; }
  .card, .btn { box-shadow: none; }
}