:root {
  --bg: #070b16;
  --bg-soft: #0d1526;
  --panel: rgba(20, 30, 52, 0.55);
  --panel-border: rgba(120, 160, 255, 0.14);
  --text: #e8edf7;
  --text-dim: #9aa8c4;
  --text-faint: #64729180;
  --accent: #5b8cff;
  --accent-2: #22d3ee;
  --accent-3: #a855f7;
  --accent-bio: #34d399;
  --radius: 18px;
  --maxw: 1080px;
  --prose: 760px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Inter", "Noto Sans JP", system-ui, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

.bg-fx {
  position: fixed;
  inset: 0;
  z-index: -2;
  background:
    radial-gradient(900px 600px at 15% -5%, rgba(91,140,255,0.22), transparent 60%),
    radial-gradient(800px 700px at 100% 0%, rgba(168,85,247,0.16), transparent 55%),
    radial-gradient(700px 700px at 50% 120%, rgba(34,211,238,0.14), transparent 60%),
    var(--bg);
}
#particles {
  position: fixed;
  inset: 0;
  z-index: -1;
  width: 100%;
  height: 100%;
  opacity: 0.7;
}
.grain {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px clamp(18px, 5vw, 48px);
  backdrop-filter: blur(14px);
  background: rgba(7, 11, 22, 0.6);
  border-bottom: 1px solid var(--panel-border);
}
.brand {
  font-weight: 800;
  letter-spacing: 0.02em;
  font-size: 1.05rem;
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  text-decoration: none;
}
.brand .dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 0 14px var(--accent);
}
.nav-links { display: flex; gap: 26px; align-items: center; }
.nav-links a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s;
}
.nav-links a:hover,
.nav-links a.active { color: var(--text); }
.nav-links .lang {
  border: 1px solid var(--panel-border);
  padding: 6px 14px;
  border-radius: 999px;
  color: var(--text);
}
.nav-links .lang:hover { border-color: var(--accent); }
@media (max-width: 720px) {
  .nav-links a:not(.lang):not(.nav-keep) { display: none; }
}

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 clamp(18px, 5vw, 32px); }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 13px 24px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.2s, box-shadow 0.2s, background 0.2s, border-color 0.2s;
  cursor: pointer;
  border: none;
  font-family: inherit;
}
.btn-primary {
  color: #04060d;
  background: linear-gradient(120deg, var(--accent-2), var(--accent));
  box-shadow: 0 8px 30px rgba(91,140,255,0.35);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 12px 40px rgba(91,140,255,0.5); }
.btn-ghost {
  color: var(--text);
  background: var(--panel);
  border: 1px solid var(--panel-border);
}
.btn-ghost:hover { transform: translateY(-2px); border-color: var(--accent); }

.sec-head { margin-bottom: 36px; }
.sec-head .kicker {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.82rem;
  color: var(--accent-2);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.sec-head h1,
.sec-head h2 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  margin: 10px 0 0;
  font-weight: 800;
  letter-spacing: -0.01em;
}
.sec-head p { color: var(--text-dim); margin: 12px 0 0; max-width: 640px; }

.tag {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.72rem;
  padding: 5px 10px;
  border-radius: 8px;
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--panel-border);
  color: var(--text-dim);
  text-decoration: none;
}
a.tag:hover {
  border-color: var(--accent);
  color: var(--text);
}

footer {
  padding: 50px 0 40px;
  text-align: center;
  color: var(--text-faint);
  font-size: 0.85rem;
  border-top: 1px solid var(--panel-border);
  margin-top: 40px;
}
footer .meta { font-family: "JetBrains Mono", monospace; margin-top: 8px; }

.reveal { opacity: 0; transform: translateY(28px); transition: opacity 0.7s ease, transform 0.7s ease; }
.reveal.in { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  #particles { display: none; }
}