:root {
  --hub-bg: #071018;
  --hub-surface: #0f2438;
  --hub-panel: rgba(15, 36, 56, 0.88);
  --teal-500: #14b8a6;
  --teal-400: #2dd4bf;
  --teal-300: #5eead4;
  --amber-500: #f59e0b;
  --amber-400: #fbbf24;
  --text: #ecfdf5;
  --text-soft: rgba(236, 253, 245, 0.72);
  --spoke: rgba(45, 212, 191, 0.35);
  --glow: rgba(20, 184, 166, 0.4);
  --radius: 14px;
  --font-body: "DM Sans", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-display: "DM Sans", "Noto Sans SC", sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 88px; }

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--text);
  background: var(--hub-bg);
  line-height: 1.78;
  font-size: 16px;
  min-height: 100vh;
  overflow-x: hidden;
}

.radial-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(circle at 50% 42%, rgba(20, 184, 166, 0.12) 0%, transparent 42%),
    radial-gradient(circle at 18% 78%, rgba(245, 158, 11, 0.08) 0%, transparent 35%),
    radial-gradient(circle at 82% 22%, rgba(45, 212, 191, 0.06) 0%, transparent 38%),
    linear-gradient(180deg, #050c14 0%, var(--hub-bg) 55%, #0a1824 100%);
}
.radial-bg::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    repeating-radial-gradient(circle at 50% 50%, transparent 0, transparent 48px, rgba(45, 212, 191, 0.04) 48px, rgba(45, 212, 191, 0.04) 49px);
  opacity: 0.65;
  pointer-events: none;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--teal-300); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--amber-400); text-decoration: underline; }

.container {
  width: min(1140px, 92vw);
  margin-inline: auto;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 200;
  padding: 0.65rem 0;
  background: rgba(7, 16, 24, 0.88);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(45, 212, 191, 0.22);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
}
.header-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  color: var(--text);
  font-weight: 600;
  font-size: 1.05rem;
  text-decoration: none;
}
.brand b {
  color: var(--amber-400);
  font-weight: 700;
}
.brand img {
  border-radius: 50%;
  border: 2px solid rgba(45, 212, 191, 0.45);
  box-shadow: 0 0 20px var(--glow);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid rgba(45, 212, 191, 0.3);
  border-radius: 50%;
  background: rgba(15, 36, 56, 0.6);
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  margin-inline: auto;
  background: var(--teal-300);
  border-radius: 2px;
  transition: transform 0.25s, opacity 0.25s;
}
.nav-toggle.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.is-open span:nth-child(2) { opacity: 0; }
.nav-toggle.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.site-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 0.5rem;
  list-style: none;
  margin: 0;
  padding: 0;
}
.site-nav a {
  color: var(--text-soft);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.45rem 1rem;
  border-radius: 999px;
  border: 1px solid transparent;
  text-decoration: none;
  transition: background 0.2s, border-color 0.2s, color 0.2s;
}
.site-nav a:hover,
.site-nav a.active {
  color: var(--text);
  background: rgba(20, 184, 166, 0.18);
  border-color: rgba(45, 212, 191, 0.35);
}

/* Ads */
.ads-top-bar {
  padding: 0.6rem 0;
  background: rgba(15, 36, 56, 0.55);
  border-bottom: 1px solid rgba(45, 212, 191, 0.15);
}
#ads {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  flex-wrap: wrap;
  background: transparent;
  margin: 10px 0;
  gap: 0.5rem;
}
#ads > div,
#ads .ads-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 70px;
}
#ads img {
  width: 65px;
  height: 65px;
  object-fit: cover;
  border-radius: 50%;
  border: 2px solid rgba(45, 212, 191, 0.3);
  transition: transform 180ms ease, box-shadow 180ms ease;
}
#ads a { display: inline-block; text-decoration: none; }
#ads img:hover {
  transform: scale(1.06);
  box-shadow: 0 0 16px var(--glow);
}
#ads figcaption,
#ads .caption {
  height: 15px;
  font-size: 11px;
  color: var(--text-soft);
  text-align: center;
  max-width: 100px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  margin-top: 4px;
}
.applist-title {
  text-align: center;
  font-size: 0.88rem;
  color: var(--text-soft);
}

/* Radial hub hero */
.hero-radial {
  padding: 2.5rem 0 1.5rem;
  text-align: center;
}
.hero-radial .intro-text {
  max-width: 680px;
  margin: 0 auto 2rem;
}
.hero-badge {
  display: inline-block;
  padding: 0.35rem 1rem;
  background: rgba(245, 158, 11, 0.15);
  border: 1px solid rgba(245, 158, 11, 0.35);
  border-radius: 999px;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  margin-bottom: 1rem;
  color: var(--amber-400);
}
.hero-radial h1 {
  font-family: var(--font-display);
  font-size: clamp(1.65rem, 4vw, 2.35rem);
  line-height: 1.32;
  margin: 0 0 1rem;
  font-weight: 700;
  color: var(--text);
}
.hero-radial .lead {
  font-size: 1.02rem;
  color: var(--text-soft);
  margin: 0;
}

.radial-stage {
  position: relative;
  width: min(720px, 94vw);
  aspect-ratio: 1;
  margin: 0 auto 2rem;
}
.radial-orbit {
  position: absolute;
  inset: 8%;
  border: 1px dashed rgba(45, 212, 191, 0.25);
  border-radius: 50%;
  pointer-events: none;
}
.radial-orbit:nth-child(2) { inset: 22%; opacity: 0.6; }
.radial-orbit:nth-child(3) { inset: 36%; opacity: 0.35; }

.hub-center {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 10;
  width: 130px;
  height: 130px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: radial-gradient(circle, rgba(20, 184, 166, 0.25) 0%, var(--hub-surface) 70%);
  border: 2px solid rgba(45, 212, 191, 0.5);
  border-radius: 50%;
  box-shadow: 0 0 40px var(--glow), inset 0 0 24px rgba(20, 184, 166, 0.12);
  text-decoration: none;
  color: var(--text);
  transition: box-shadow 0.3s, transform 0.3s;
}
.hub-center:hover {
  box-shadow: 0 0 56px rgba(245, 158, 11, 0.35), inset 0 0 28px rgba(20, 184, 166, 0.18);
  transform: translate(-50%, -50%) scale(1.04);
  text-decoration: none;
  color: var(--text);
}
.hub-center img {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  margin-bottom: 0.35rem;
}
.hub-center span {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--teal-300);
}

.radial-spoke {
  --angle: 0deg;
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  transform: rotate(var(--angle));
  z-index: 5;
}
.spoke-line {
  position: absolute;
  top: 0;
  left: 0;
  width: 2px;
  height: calc(min(720px, 94vw) * 0.28);
  background: linear-gradient(to bottom, rgba(45, 212, 191, 0.55), rgba(45, 212, 191, 0.08));
  transform-origin: top center;
  transform: translateX(-50%);
}
.spoke-node {
  position: absolute;
  top: calc(min(720px, 94vw) * 0.28);
  left: 0;
  transform: translate(-50%, -50%) rotate(calc(-1 * var(--angle)));
  min-width: 88px;
  max-width: 110px;
  padding: 0.55rem 0.65rem;
  background: var(--hub-panel);
  border: 1px solid rgba(45, 212, 191, 0.3);
  border-radius: var(--radius);
  text-align: center;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text);
  text-decoration: none;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  transition: border-color 0.2s, box-shadow 0.2s, color 0.2s;
}
.spoke-node:hover {
  border-color: var(--amber-400);
  box-shadow: 0 8px 28px rgba(245, 158, 11, 0.2);
  color: var(--amber-400);
  text-decoration: none;
}
.spoke-node small {
  display: block;
  font-size: 0.65rem;
  font-weight: 400;
  color: var(--text-soft);
  margin-top: 0.15rem;
}

/* Partner strip */
.partner-strip {
  padding: 0.5rem 0 1rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
}
.partner-strip a {
  display: inline-flex;
  align-items: center;
  padding: 0.55rem 1.25rem;
  background: rgba(15, 36, 56, 0.75);
  border: 1px solid rgba(45, 212, 191, 0.3);
  border-radius: 999px;
  color: var(--teal-300);
  font-size: 0.88rem;
  font-weight: 500;
  text-decoration: none;
  transition: background 0.2s, border-color 0.2s;
}
.partner-strip a:hover {
  background: rgba(20, 184, 166, 0.15);
  border-color: var(--amber-400);
  color: var(--amber-400);
  text-decoration: none;
}

/* Anchor ring nav */
.ring-nav {
  padding: 0.75rem 0 1.25rem;
  overflow-x: auto;
}
.ring-scroll {
  display: flex;
  flex-wrap: nowrap;
  gap: 0.55rem;
  padding-bottom: 0.35rem;
  justify-content: center;
}
.ring-scroll a {
  flex-shrink: 0;
  padding: 0.48rem 1.05rem;
  background: rgba(15, 36, 56, 0.7);
  border: 1px solid rgba(45, 212, 191, 0.25);
  border-radius: 999px;
  font-size: 0.84rem;
  color: var(--text-soft);
  text-decoration: none;
  transition: background 0.2s, color 0.2s;
}
.ring-scroll a:hover {
  background: rgba(20, 184, 166, 0.18);
  color: var(--text);
}

/* Content panels */
.section-stack {
  padding: 0 0 3rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}
.radial-panel {
  background: var(--hub-panel);
  border: 1px solid rgba(45, 212, 191, 0.22);
  border-radius: var(--radius);
  padding: 2rem 2.25rem;
  position: relative;
  overflow: hidden;
}
.radial-panel::before {
  content: "";
  position: absolute;
  top: -40px;
  right: -40px;
  width: 120px;
  height: 120px;
  border: 1px dashed rgba(45, 212, 191, 0.15);
  border-radius: 50%;
  pointer-events: none;
}
.radial-panel h2 {
  font-family: var(--font-display);
  font-size: clamp(1.3rem, 3vw, 1.8rem);
  margin: 0 0 1.1rem;
  font-weight: 600;
  color: var(--text);
}
.prose { max-width: 72ch; }
.prose p { margin: 0 0 1rem; color: var(--text-soft); }
.prose ul, .prose ol { margin: 0 0 1rem; padding-left: 1.4rem; color: var(--text-soft); }
.prose li { margin-bottom: 0.4rem; }
.prose strong { color: var(--text); }
.prose h3 {
  font-size: 1.05rem;
  color: var(--teal-300);
  margin: 1.25rem 0 0.65rem;
}

.split-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  align-items: center;
}
.split-row.reverse { direction: rtl; }
.split-row.reverse > * { direction: ltr; }
.split-row img {
  border-radius: var(--radius);
  border: 1px solid rgba(45, 212, 191, 0.25);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.35);
}

/* Topic ring cards */
.topic-ring {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}
.topic-card {
  background: rgba(7, 16, 24, 0.55);
  border: 1px solid rgba(45, 212, 191, 0.2);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color 0.2s, transform 0.2s;
}
.topic-card:hover {
  border-color: rgba(245, 158, 11, 0.4);
  transform: translateY(-3px);
}
.topic-card img {
  width: 100%;
  height: 150px;
  object-fit: cover;
  border-bottom: 1px solid rgba(45, 212, 191, 0.15);
}
.topic-card .card-body { padding: 1rem 1.15rem 1.2rem; }
.topic-card h3 {
  margin: 0 0 0.45rem;
  font-size: 1rem;
  color: var(--text);
}
.topic-card p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--text-soft);
}

/* FAQ */
.faq-list {
  margin-top: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}
.faq-item {
  background: rgba(7, 16, 24, 0.5);
  border: 1px solid rgba(45, 212, 191, 0.18);
  border-radius: var(--radius);
  padding: 1.15rem 1.4rem;
}
.faq-item h3 {
  margin: 0 0 0.45rem;
  font-size: 0.98rem;
  color: var(--teal-300);
}
.faq-item p { margin: 0; font-size: 0.93rem; color: var(--text-soft); }

/* Related reading */
.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1.25rem;
  margin-top: 1.25rem;
}
.related-item {
  background: rgba(7, 16, 24, 0.5);
  border: 1px solid rgba(45, 212, 191, 0.2);
  border-radius: var(--radius);
  padding: 1.15rem 1.3rem;
  min-height: 120px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: border-color 0.2s;
}
.related-item:hover { border-color: rgba(245, 158, 11, 0.35); }
.related-item h3 {
  margin: 0 0 0.5rem;
  font-size: 0.95rem;
  color: var(--text);
}
.related-item p {
  margin: 0 0 0.75rem;
  font-size: 0.86rem;
  color: var(--text-soft);
  flex: 1;
}
.related-item a.read-more {
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--teal-300);
  text-decoration: none;
}
.related-item a.read-more:hover { color: var(--amber-400); }

/* Inner pages */
.page-hero { padding: 2.25rem 0 1.25rem; }
.page-hero-inner {
  background: var(--hub-panel);
  border: 1px solid rgba(45, 212, 191, 0.22);
  border-radius: var(--radius);
  padding: 1.75rem 2rem;
}
.page-hero h1 {
  font-family: var(--font-display);
  font-size: clamp(1.45rem, 3vw, 2rem);
  margin: 0.5rem 0 0;
  font-weight: 600;
}
.breadcrumb { font-size: 0.86rem; color: var(--text-soft); }
.breadcrumb a { color: var(--teal-300); }

/* Error pages */
.error-wrap {
  text-align: center;
  padding: 4rem 0 5rem;
}
.error-panel {
  display: inline-block;
  background: var(--hub-panel);
  border: 1px solid rgba(45, 212, 191, 0.25);
  border-radius: var(--radius);
  padding: 3rem 4rem;
}
.error-wrap .code {
  font-family: var(--font-display);
  font-size: 5rem;
  font-weight: 700;
  margin: 0;
  line-height: 1;
  background: linear-gradient(135deg, var(--teal-300), var(--amber-400));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.error-wrap h1 { margin: 0.5rem 0 1rem; color: var(--text); }
.error-wrap p { color: var(--text-soft); }

/* Footer */
.site-footer {
  padding: 2rem 0 2.5rem;
  margin-top: 1rem;
  border-top: 1px solid rgba(45, 212, 191, 0.2);
  background: rgba(7, 16, 24, 0.85);
  font-size: 0.86rem;
  text-align: center;
  color: var(--text-soft);
}
.site-footer a { color: var(--teal-300); }
.footer-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem 1.5rem;
  margin-bottom: 1rem;
}
.footer-links a { text-decoration: none; }

@media (max-width: 860px) {
  .nav-toggle { display: flex; }
  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: rgba(7, 16, 24, 0.96);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(45, 212, 191, 0.22);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s;
  }
  .site-nav.is-open { max-height: 320px; }
  .site-nav ul {
    flex-direction: column;
    padding: 1rem 1.25rem 1.25rem;
  }
  .header-row { position: relative; }

  .radial-stage {
    aspect-ratio: auto;
    height: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    padding: 1rem 0;
  }
  .radial-orbit { display: none; }
  .hub-center {
    position: relative;
    top: auto;
    left: auto;
    transform: none;
    margin-bottom: 0.5rem;
  }
  .hub-center:hover { transform: scale(1.04); }
  .radial-spoke {
    position: relative;
    top: auto;
    left: auto;
    width: 100%;
    height: auto;
    transform: none;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0 0.5rem;
  }
  .spoke-line { display: none; }
  .spoke-node {
    position: relative;
    top: auto;
    left: auto;
    transform: none;
    max-width: none;
    width: 100%;
    text-align: left;
    padding: 0.75rem 1rem;
  }
  .split-row,
  .split-row.reverse { grid-template-columns: 1fr; direction: ltr; }
  .radial-panel { padding: 1.5rem 1.35rem; }
  #ads { flex-wrap: nowrap; overflow-x: auto; justify-content: flex-start; }
  .ring-scroll { justify-content: flex-start; }
}