:root {
  --bg: #0a1018;
  --bg-soft: #121c28;
  --surface: rgba(18, 28, 40, 0.72);
  --surface-border: rgba(141, 167, 196, 0.22);
  --text: #ecf2f8;
  --muted: #a7b7ca;
  --accent: #35d7ff;
  --accent-2: #88ffce;
  --shadow: 0 16px 40px rgba(0, 0, 0, 0.35);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Noto Sans JP", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 10% 12%, #112339 0%, transparent 34%),
    radial-gradient(circle at 85% 18%, #1e1f3f 0%, transparent 30%),
    linear-gradient(160deg, var(--bg) 0%, #080c13 55%, #0f1824 100%);
  min-height: 100vh;
  line-height: 1.7;
}

.bg-glow {
  position: fixed;
  z-index: -1;
  filter: blur(60px);
  opacity: 0.35;
  pointer-events: none;
}

.bg-glow-a {
  width: 280px;
  height: 280px;
  background: #00cfff;
  top: 8%;
  left: -90px;
}

.bg-glow-b {
  width: 320px;
  height: 320px;
  background: #6a7dff;
  right: -120px;
  bottom: 12%;
}

.site-header,
main,
.site-footer {
  width: min(1120px, 92%);
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  margin-top: 10px;
  padding: 12px 18px;
  border: 1px solid var(--surface-border);
  border-radius: 14px;
  backdrop-filter: blur(10px);
  background: rgba(7, 11, 18, 0.6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  z-index: 20;
}

.logo {
  font-family: "Orbitron", sans-serif;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--text);
  text-decoration: none;
}

.site-nav {
  display: flex;
  gap: 18px;
}

.site-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.95rem;
}

.site-nav a:hover {
  color: var(--accent);
}

.section {
  margin-top: 56px;
}

.hero {
  padding: 52px 30px;
  border-radius: 22px;
  background: linear-gradient(145deg, rgba(17, 27, 40, 0.85), rgba(16, 18, 30, 0.78));
  border: 1px solid var(--surface-border);
  box-shadow: var(--shadow);
}

.eyebrow {
  margin: 0;
  color: var(--accent-2);
  font-size: 0.84rem;
  letter-spacing: 0.12em;
  font-family: "Orbitron", sans-serif;
}

.hero h1 {
  margin: 10px 0 12px;
  font-size: clamp(2rem, 4.8vw, 3.4rem);
  line-height: 1.2;
}

.lead {
  margin: 0;
  color: #d4e1ef;
  max-width: 60ch;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.btn {
  display: inline-block;
  text-decoration: none;
  border-radius: 999px;
  font-weight: 700;
  padding: 11px 20px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: linear-gradient(90deg, var(--accent), #6dbdff);
  color: #06111d;
  box-shadow: 0 10px 25px rgba(53, 215, 255, 0.28);
}

.btn-ghost {
  border: 1px solid rgba(236, 242, 248, 0.3);
  color: var(--text);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.card {
  padding: 24px;
  border-radius: 16px;
  background: var(--surface);
  border: 1px solid var(--surface-border);
  box-shadow: var(--shadow);
}

.card h2,
.section-title,
.join-card h2 {
  margin-top: 0;
  margin-bottom: 12px;
  font-size: clamp(1.3rem, 2.6vw, 1.9rem);
}

.card ul {
  margin: 0;
  padding-left: 1.2rem;
}

.timeline {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.timeline-item {
  padding: 20px;
  border-radius: 14px;
  background: var(--surface);
  border: 1px solid var(--surface-border);
}

.timeline-item h3 {
  margin-top: 0;
  margin-bottom: 10px;
  color: var(--accent-2);
}

.archive-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.archive-card {
  padding: 22px;
  border-radius: 14px;
  background: var(--surface);
  border: 1px solid var(--surface-border);
}

.archive-tag {
  display: inline-block;
  margin: 0 0 8px;
  padding: 2px 10px;
  border-radius: 999px;
  font-size: 0.78rem;
  color: #06111d;
  background: linear-gradient(90deg, var(--accent-2), #9be4ff);
  font-weight: 700;
}

.archive-card h3 {
  margin: 0 0 10px;
  font-size: 1.35rem;
}

.archive-meta {
  margin: 14px 0;
  padding-left: 1.2rem;
}

.archive-link {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px dashed rgba(53, 215, 255, 0.45);
  padding-bottom: 2px;
}

.archive-link[aria-disabled="true"] {
  cursor: default;
  pointer-events: none;
  opacity: 0.8;
}

.join-card {
  padding: 26px;
  border-radius: 16px;
  background: linear-gradient(165deg, rgba(18, 34, 46, 0.85), rgba(18, 24, 33, 0.9));
  border: 1px solid var(--surface-border);
  box-shadow: var(--shadow);
}

.note {
  color: var(--muted);
  font-size: 0.9rem;
}

.faq details {
  margin-bottom: 10px;
  padding: 16px;
  border-radius: 12px;
  background: var(--surface);
  border: 1px solid var(--surface-border);
}

.faq summary {
  cursor: pointer;
  font-weight: 600;
}

.site-footer {
  padding: 40px 0 48px;
  color: var(--muted);
  font-size: 0.9rem;
}

@media (max-width: 900px) {
  .card-grid,
  .timeline,
  .archive-grid {
    grid-template-columns: 1fr;
  }

  .site-header {
    flex-direction: column;
    gap: 10px;
  }
}

@media (max-width: 640px) {
  .hero {
    padding: 40px 20px;
  }

  .site-nav {
    width: 100%;
    justify-content: space-between;
    gap: 8px;
  }

  .site-nav a {
    font-size: 0.86rem;
  }

  .section {
    margin-top: 42px;
  }
}