:root {
  --bg: #08152a;
  --panel: rgba(10, 24, 48, 0.82);
  --panel-soft: rgba(255, 255, 255, 0.08);
  --text: #eff5ff;
  --muted: #b9c7de;
  --brand: #64d4ff;
  --accent: #ffd166;
  --line: rgba(255, 255, 255, 0.12);
  --shadow: 0 24px 60px rgba(0, 0, 0, 0.28);
  --radius: 20px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at top, rgba(100, 212, 255, 0.18), transparent 36%),
    linear-gradient(135deg, #071224 0%, #0b1f3d 55%, #102b56 100%);
}

a {
  color: inherit;
}

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

.page {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding-bottom: 48px;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 28px 0 16px;
}

.site-header__brand {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.site-header__logo {
  font-size: clamp(2rem, 4vw, 3.4rem);
  font-weight: 800;
  text-decoration: none;
  letter-spacing: 0.04em;
  color: var(--brand);
}

.site-header__badge {
  margin: 0;
  color: var(--muted);
}

.site-header__contact {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 18px;
  border-radius: 999px;
  text-decoration: none;
  color: #09203f;
  background: var(--accent);
  font-weight: 700;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(5, 14, 28, 0.68);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 8px;
  z-index: 20;
}

.site-nav__item {
  position: relative;
}

.site-nav__item.has-children {
  padding-bottom: 10px;
  margin-bottom: -10px;
}

.site-nav__item.has-children::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 100%;
  height: 12px;
}

.site-nav__link,
.site-nav__dropdown-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 0 16px;
  border-radius: 999px;
  text-decoration: none;
  color: var(--text);
}

.site-nav__link:hover,
.site-nav__link.is-active,
.site-nav__dropdown-link:hover {
  background: rgba(255, 255, 255, 0.1);
}

.site-nav__dropdown {
  position: absolute;
  left: 0;
  top: calc(100% + 4px);
  display: none;
  min-width: 180px;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: #0a1830;
  box-shadow: var(--shadow);
  z-index: 30;
}

.site-nav__item.has-children:hover .site-nav__dropdown,
.site-nav__item.has-children:focus-within .site-nav__dropdown,
.site-nav__item.has-children.is-open .site-nav__dropdown {
  display: grid;
  gap: 6px;
}

.hero,
.cta-panel,
.problem,
.about-panel,
.download-section,
.article-layout,
.footer {
  margin-top: 24px;
}

.hero {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 24px;
  padding: 32px;
  border: 1px solid var(--line);
  border-radius: 28px;
  background: linear-gradient(145deg, rgba(8, 21, 42, 0.92), rgba(15, 39, 74, 0.8));
  box-shadow: var(--shadow);
}

.hero__eyebrow,
.problem__eyebrow {
  margin: 0 0 10px;
  color: var(--brand);
  font-size: 0.88rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 0;
  font-size: clamp(2.2rem, 5vw, 4.2rem);
  line-height: 1.05;
}

.hero__lead {
  max-width: 680px;
  color: var(--muted);
  font-size: 1.05rem;
  line-height: 1.8;
}

.stats {
  display: grid;
  gap: 16px;
}

.stat-item,
.card,
.article-section,
.about-card,
.download-box {
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel-soft);
}

.stat-number {
  font-size: 2rem;
  font-weight: 800;
  color: var(--accent);
}

.showcase {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.card {
  background: rgba(255, 255, 255, 0.96);
  color: #0e2445;
}

.card img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  border-radius: 14px;
  margin-bottom: 14px;
}

.cta-panel,
.about-panel {
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: var(--panel);
}

.cta-panel h2,
.problems-title,
.about-header h1,
.download-box h1 {
  margin-top: 0;
}

.cta {
  display: flex;
  justify-content: center;
  margin-top: 20px;
}

.cta--hero,
.cta--left {
  justify-content: flex-start;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 22px;
  border: 0;
  border-radius: 999px;
  color: #09203f;
  background: var(--accent);
  text-decoration: none;
  font-weight: 700;
  cursor: pointer;
}

.button--small {
  min-height: 38px;
  padding: 0 14px;
  font-size: 0.92rem;
}

.problems {
  display: grid;
  gap: 24px;
}

.problem {
  display: grid;
  grid-template-columns: 1.3fr 0.9fr;
  gap: 20px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: rgba(5, 18, 35, 0.72);
}

.theory-box {
  padding: 24px;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.05);
}

.theory-box h3,
.article-section h2 {
  margin-top: 0;
}

.problem__highlights {
  padding-left: 18px;
  color: var(--muted);
  line-height: 1.8;
}

.side-boxes {
  display: grid;
  gap: 18px;
}

.simulation-box {
  position: relative;
  min-height: 190px;
  padding: 22px;
  border-radius: 18px;
  overflow: hidden;
  text-decoration: none;
  color: var(--text);
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  background-image: var(--bg-url);
  background-size: cover;
  background-position: center;
}

.simulation-box .overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent, rgba(4, 10, 24, 0.85));
}

.simulation-box h4,
.simulation-box p {
  position: relative;
  z-index: 1;
  margin: 0;
}

.simulation-box p {
  margin-top: 8px;
  color: #dce7f8;
}

.article-layout {
  display: grid;
  grid-template-columns: minmax(260px, 340px) 1fr;
  gap: 24px;
  align-items: start;
}

.article-list {
  display: grid;
  gap: 16px;
}

.article-section {
  text-align: left;
  color: var(--text);
  cursor: pointer;
}

.article-section p,
.about-header p,
.about-card p {
  color: var(--muted);
}

.markdown-shell {
  min-height: 420px;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: rgba(255, 255, 255, 0.95);
  color: #0f2343;
  line-height: 1.8;
}

.markdown-shell pre {
  overflow: auto;
}

.markdown-shell--error {
  color: #8f1d1d;
}

.about-header,
.footer {
  text-align: center;
}

.about-grid,
.download-section {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.download-box {
  min-height: 220px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.footer {
  padding: 28px 0 40px;
  color: var(--muted);
}

.footer__record {
  margin-top: 8px;
}

.record-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}

.record-icon {
  width: 18px;
  height: 18px;
  object-fit: contain;
}

@media (max-width: 960px) {
  .hero,
  .problem,
  .article-layout,
  .about-grid,
  .download-section,
  .showcase {
    grid-template-columns: 1fr;
  }

  .site-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .site-nav {
    border-radius: 24px;
  }
}

@media (max-width: 640px) {
  .page {
    width: min(100% - 20px, 1180px);
  }

  .hero,
  .problem,
  .cta-panel,
  .about-panel,
  .markdown-shell,
  .stat-item,
  .card,
  .article-section,
  .about-card,
  .download-box {
    padding: 18px;
  }

  .site-nav {
    position: static;
  }
}