*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --deep-blue: #1B3A5C;
  --sky-blue: #2E6E8E;
  --bright-blue: #5A9BD5;
  --orange: #F5A623;
  --green: #7CB342;
  --light-gray: #E8EEF2;
  --ink: #1A1A2E;
  --white: #FFFFFF;
  --header-width: clamp(220px, 25vw, 320px);
  --header-height-mobile: 64px;
  --border-w: 2px;
  --shadow: 4px 4px 0 rgba(27, 58, 92, 0.3);
  --font-head: "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", sans-serif;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--light-gray);
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-head);
  font-weight: 900;
  line-height: 1.25;
  color: var(--ink);
}

p {
  margin-bottom: 1em;
}

a {
  color: var(--bright-blue);
  transition: color 0.2s ease;
}

a:hover {
  color: var(--orange);
}

::selection {
  background: var(--orange);
  color: var(--ink);
}

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

#main-content {
  scroll-margin-top: calc(var(--header-height-mobile) + 16px);
}

#main-content:focus {
  outline: none;
}

.body-lock {
  overflow: hidden;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 32px;
}

.content-block {
  max-width: 960px;
  margin: 0 auto;
  padding: 40px 0;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  list-style: none;
  padding: 16px 0;
  margin-bottom: 16px;
  border-bottom: 2px solid rgba(27, 58, 92, 0.12);
  font-size: 14px;
}

.breadcrumb a {
  color: var(--bright-blue);
  text-decoration: none;
}

.breadcrumb a:hover {
  color: var(--orange);
  text-decoration: underline;
}

.breadcrumb li + li::before {
  content: "/";
  margin-right: 6px;
  color: rgba(26, 26, 46, 0.35);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  font-family: var(--font-head);
  font-weight: 900;
  font-size: 16px;
  line-height: 1;
  text-decoration: none;
  border: 2px solid var(--deep-blue);
  background: var(--white);
  color: var(--deep-blue);
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease, color 0.15s ease;
}

.btn:hover {
  transform: translate(2px, 2px);
  box-shadow: 2px 2px 0 rgba(27, 58, 92, 0.3);
  color: var(--deep-blue);
}

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

.btn-primary:hover {
  box-shadow: 6px 6px 0 rgba(26, 26, 46, 0.35);
  background: var(--bright-blue);
  color: var(--white);
  border-color: var(--white);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

.card {
  background: var(--white);
  border: 2px solid var(--deep-blue);
  box-shadow: var(--shadow);
  padding: 24px;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.card:hover {
  transform: translate(-2px, -2px);
  box-shadow: 6px 6px 0 rgba(27, 58, 92, 0.3);
}

.media-frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: linear-gradient(135deg, rgba(46, 110, 142, 0.9) 0%, rgba(27, 58, 92, 0.95) 100%);
  border: 2px solid var(--deep-blue);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.media-frame::after {
  content: "LD·图";
  position: absolute;
  inset: 0;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  letter-spacing: 4px;
  color: rgba(255, 255, 255, 0.55);
}

.media-frame img {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--header-width);
  background: var(--deep-blue);
  color: var(--white);
  border-right: 3px solid var(--orange);
  z-index: 1000;
}

.skip-link {
  position: absolute;
  top: -120px;
  left: 12px;
  z-index: 1100;
  background: var(--orange);
  color: var(--ink);
  padding: 12px 20px;
  font-weight: 700;
  text-decoration: none;
  border: 2px solid var(--ink);
  box-shadow: 4px 4px 0 rgba(0, 0, 0, 0.2);
}

.skip-link:focus {
  top: 12px;
}

.scroll-progress {
  position: absolute;
  top: 0;
  left: 0;
  width: 0%;
  height: 4px;
  background: var(--orange);
  z-index: 1050;
  pointer-events: none;
}

.header-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: 24px;
  overflow-y: auto;
}

.header-flag {
  display: flex;
  height: 6px;
  width: 100%;
  margin-bottom: 24px;
}

.flag-stripe {
  flex: 1;
  height: 100%;
}

.flag-stripe-blue {
  background: var(--bright-blue);
}

.flag-stripe-white {
  background: var(--white);
}

.flag-stripe-orange {
  background: var(--orange);
}

.flag-stripe-green {
  background: var(--green);
}

.brand-link {
  display: block;
  text-decoration: none;
  margin-bottom: 32px;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  background: var(--orange);
  color: var(--ink);
  font-family: var(--font-head);
  font-weight: 900;
  font-size: 22px;
  border: 2px solid var(--ink);
  box-shadow: 4px 4px 0 rgba(0, 0, 0, 0.25);
  margin-bottom: 12px;
}

.brand-name {
  display: block;
  font-family: var(--font-head);
  font-size: 28px;
  font-weight: 900;
  color: var(--white);
  line-height: 1.2;
}

.brand-sub {
  display: block;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.65);
  letter-spacing: 2px;
}

.site-nav {
  flex: 1;
}

.nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-item {
  margin-bottom: 4px;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 14px;
  text-decoration: none;
  color: rgba(255, 255, 255, 0.78);
  border-left: 4px solid transparent;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.nav-link:hover,
.nav-link:focus-visible {
  background: rgba(255, 255, 255, 0.07);
  color: var(--white);
  border-left-color: var(--orange);
}

.nav-link[aria-current="page"] {
  background: rgba(90, 155, 213, 0.22);
  color: var(--white);
  border-left-color: var(--orange);
}

.nav-index {
  font-size: 12px;
  color: var(--orange);
  font-weight: 700;
  min-width: 24px;
}

.nav-text {
  font-family: var(--font-head);
  font-size: 16px;
  font-weight: 700;
}

.header-side {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 16px;
}

.header-notice {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-left: 4px solid var(--green);
  background: rgba(255, 255, 255, 0.06);
  font-size: 13px;
  color: rgba(255, 255, 255, 0.75);
}

.notice-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--green);
  display: inline-block;
  flex-shrink: 0;
}

.btn-download {
  background: var(--orange);
  border-color: var(--ink);
  color: var(--ink);
  box-shadow: 4px 4px 0 rgba(0, 0, 0, 0.25);
  justify-content: center;
  font-size: 14px;
  padding: 10px 16px;
}

.btn-download:hover {
  background: var(--bright-blue);
  color: var(--white);
  border-color: var(--white);
  box-shadow: 6px 6px 0 rgba(0, 0, 0, 0.3);
  transform: translate(-1px, -1px);
}

.header-vertical {
  position: absolute;
  right: 12px;
  bottom: 40px;
  writing-mode: vertical-rl;
  font-size: 12px;
  letter-spacing: 6px;
  color: rgba(255, 255, 255, 0.22);
  pointer-events: none;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  margin-left: auto;
  background: transparent;
  border: none;
  padding: 12px 10px;
  cursor: pointer;
}

.nav-toggle-bar {
  display: block;
  width: 24px;
  height: 3px;
  background: var(--white);
  border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.25s ease, background 0.25s ease;
}

.nav-toggle-label {
  display: block;
  font-size: 11px;
  line-height: 1;
  color: rgba(255, 255, 255, 0.7);
  letter-spacing: 2px;
  margin-top: 4px;
}

.nav-toggle:hover .nav-toggle-bar {
  background: var(--orange);
}

.nav-toggle.is-active .nav-toggle-bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.is-active .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle.is-active .nav-toggle-bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.site-footer {
  background: var(--deep-blue);
  color: rgba(255, 255, 255, 0.75);
  border-top: 4px solid var(--orange);
  position: relative;
  padding: 48px 4vw 24px;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: -4px;
  left: 0;
  width: 180px;
  height: 4px;
  background: var(--green);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1.6fr;
  gap: 40px;
  max-width: 1200px;
  margin: 0 auto;
}

.footer-brand-name {
  font-family: var(--font-head);
  font-size: 26px;
  font-weight: 900;
  color: var(--white);
  margin-bottom: 8px;
}

.footer-brand-sub {
  font-size: 14px;
  color: rgba(255, 255, 255, 0.55);
  margin-bottom: 16px;
}

.footer-nav {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-link {
  color: var(--bright-blue);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  padding: 4px 0;
}

.footer-link:hover {
  color: var(--orange);
  text-decoration: underline;
}

.footer-contact p {
  margin-bottom: 4px;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.65);
}

.footer-bottom {
  max-width: 1200px;
  margin: 32px auto 0;
  padding-top: 20px;
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  text-align: center;
  font-size: 13px;
  color: rgba(255, 255, 255, 0.45);
}

@media (min-width: 768px) {
  body {
    padding-left: var(--header-width);
  }
}

@media (min-width: 768px) and (max-width: 1023px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .footer-contact {
    grid-column: 1 / -1;
  }
}

@media (max-width: 767px) {
  body {
    padding-top: var(--header-height-mobile);
    padding-left: 0;
  }

  .site-header {
    width: 100%;
    height: var(--header-height-mobile);
    bottom: auto;
    border-right: none;
    border-bottom: 3px solid var(--orange);
  }

  .header-inner {
    flex-direction: row;
    align-items: center;
    padding: 0 16px;
    height: var(--header-height-mobile);
    overflow: visible;
  }

  .scroll-progress {
    height: 3px;
  }

  .header-flag {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    margin: 0;
  }

  .brand-link {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 0;
  }

  .brand-mark {
    width: 40px;
    height: 40px;
    font-size: 16px;
    box-shadow: 2px 2px 0 rgba(0, 0, 0, 0.25);
    margin-bottom: 0;
  }

  .brand-name,
  .brand-sub {
    display: none;
  }

  .site-nav {
    position: fixed;
    top: var(--header-height-mobile);
    left: 0;
    right: 0;
    width: 100%;
    background: var(--deep-blue);
    max-height: calc(100vh - var(--header-height-mobile));
    overflow-y: auto;
    transform: translateY(-10px);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s;
    border-bottom: 3px solid var(--orange);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  }

  .site-nav[data-open] {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-list {
    padding: 12px 16px;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .header-side {
    display: none;
  }

  .header-vertical {
    display: none;
  }

  .media-frame {
    aspect-ratio: 4 / 3;
  }

  .container {
    padding: 0 20px;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}