:root {
  --bg: #0a0a0f;
  --surface: #1a1a22;
  --border: rgba(255, 255, 255, 0.12);
  --text: #f5f5f7;
  --muted: rgba(235, 235, 245, 0.55);
  --accent: #64d2ff;
  --green: #30d158;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Hiragino Sans", "Noto Sans JP", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 32px 20px 48px;
}

.hero {
  margin-bottom: 28px;
}

.eyebrow {
  margin: 0 0 8px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

h1 {
  margin: 0 0 10px;
  font-size: 2rem;
  letter-spacing: 0.02em;
}

h2 {
  margin: 28px 0 12px;
  font-size: 1.25rem;
}

h3 {
  margin: 20px 0 8px;
  font-size: 1rem;
  color: var(--accent);
}

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

.topnav {
  margin-bottom: 24px;
  font-size: 14px;
}

.topnav a {
  margin-right: 16px;
}

.cards {
  display: grid;
  gap: 14px;
  margin: 24px 0 32px;
}

.card {
  display: block;
  padding: 18px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  color: inherit;
  text-decoration: none;
  transition: border-color 0.15s ease;
}

.card:hover {
  border-color: rgba(100, 210, 255, 0.45);
  text-decoration: none;
}

.card h2 {
  margin: 0 0 6px;
  font-size: 1.1rem;
}

.card p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.panel {
  padding: 20px 22px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  margin-bottom: 18px;
}

.panel p:last-child,
.panel ul:last-child {
  margin-bottom: 0;
}

ul, ol {
  padding-left: 1.25rem;
}

li + li {
  margin-top: 6px;
}

.note {
  padding: 16px 18px;
  border: 1px dashed var(--border);
  border-radius: 12px;
  color: var(--muted);
  font-size: 14px;
}

.note h2 {
  margin-top: 0;
  font-size: 1rem;
  color: var(--text);
}

code {
  padding: 2px 6px;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.06);
  font-size: 0.92em;
  word-break: break-all;
}

.contact-box {
  margin-top: 24px;
  padding: 16px 18px;
  border-left: 3px solid var(--green);
  background: rgba(48, 209, 88, 0.08);
  border-radius: 0 12px 12px 0;
}

footer {
  margin-top: 40px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 14px;
}

@media (max-width: 480px) {
  h1 {
    font-size: 1.65rem;
  }
}