:root {
  color-scheme: dark light;
  --bg: #181D24;
  --surface: #222831;
  --border: #2E3742;
  --text: #E6E8EB;
  --text-muted: #9BA3AE;
  --accent: #7AC1FF;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #F7F8FA;
    --surface: #FFFFFF;
    --border: #E2E5EA;
    --text: #1A1F26;
    --text-muted: #5A6472;
    --accent: #2176C8;
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #181D24;
  --surface: #222831;
  --border: #2E3742;
  --text: #E6E8EB;
  --text-muted: #9BA3AE;
  --accent: #7AC1FF;
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #F7F8FA;
  --surface: #FFFFFF;
  --border: #E2E5EA;
  --text: #1A1F26;
  --text-muted: #5A6472;
  --accent: #2176C8;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans",
               "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic",
               Meiryo, sans-serif;
  font-size: 16px;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 24px 80px;
}

header.page-header {
  border-bottom: 1px solid var(--border);
  padding-bottom: 24px;
  margin-bottom: 32px;
}

.back-link {
  display: inline-block;
  color: var(--accent);
  text-decoration: none;
  font-size: 14px;
  margin-bottom: 16px;
}

.back-link:hover { text-decoration: underline; }

h1 {
  font-size: 28px;
  font-weight: 700;
  margin: 0 0 8px;
  letter-spacing: 0.02em;
}

.lead {
  color: var(--text-muted);
  margin: 0;
  font-size: 15px;
}

h2 {
  font-size: 20px;
  font-weight: 700;
  margin: 40px 0 12px;
  padding-left: 12px;
  border-left: 3px solid var(--accent);
}

h3 {
  font-size: 16px;
  font-weight: 600;
  margin: 24px 0 8px;
  color: var(--text);
}

p { margin: 12px 0; }

ul, ol {
  padding-left: 1.5em;
  margin: 12px 0;
}

li { margin: 6px 0; }

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

a:hover { text-decoration: underline; }

.info-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 24px;
  margin: 16px 0;
}

.info-card p { margin: 6px 0; }

.revision {
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 14px;
}

.revision p { margin: 4px 0; }

@media (max-width: 480px) {
  .container { padding: 24px 16px 48px; }
  h1 { font-size: 24px; }
  h2 { font-size: 18px; }
}