:root {
  --fg: #1c1c1e;
  --muted: #6b6b6f;
  --bg: #ffffff;
  --bg-alt: #f7f7f8;
  --border: #e3e3e6;
  --accent: #ff5a4a;
  --max-width: 720px;
  --radius: 10px;
}

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  padding: 0;
  color: var(--fg);
  background: var(--bg);
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN",
    "Hiragino Sans", "Noto Sans JP", Meiryo, sans-serif;
  font-size: 16px;
  line-height: 1.7;
}

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

a:hover {
  text-decoration: underline;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: saturate(180%) blur(8px);
}

.site-header .brand {
  font-weight: 700;
  font-size: 20px;
  color: var(--fg);
}

.site-header nav a {
  margin-left: 16px;
  color: var(--muted);
  font-size: 14px;
}

main.prose {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 20px 64px;
  word-break: break-word;
  overflow-wrap: anywhere;
}

.prose h1 {
  font-size: 28px;
  margin: 0 0 24px;
  line-height: 1.3;
}

.prose h2 {
  font-size: 20px;
  margin: 32px 0 12px;
  padding-top: 8px;
  border-top: 1px solid var(--border);
}

.prose h3 {
  font-size: 17px;
  margin: 24px 0 8px;
}

.prose p,
.prose li {
  font-size: 15px;
}

.prose ul,
.prose ol {
  padding-left: 1.4em;
}

.prose blockquote {
  margin: 16px 0;
  padding: 12px 16px;
  background: var(--bg-alt);
  border-left: 3px solid var(--accent);
  color: var(--muted);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 14px;
}

.prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 14px;
  display: block;
  overflow-x: auto;
}

.prose th,
.prose td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
  vertical-align: top;
}

.prose th {
  background: var(--bg-alt);
}

.prose code {
  background: var(--bg-alt);
  padding: 2px 6px;
  border-radius: 6px;
  font-size: 0.9em;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.prose pre {
  background: var(--bg-alt);
  padding: 12px 16px;
  border-radius: var(--radius);
  overflow-x: auto;
}

.prose pre code {
  background: transparent;
  padding: 0;
}

.site-footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 24px 20px 48px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 13px;
  text-align: center;
}

/* Landing-only */
.hero {
  text-align: center;
  padding: 48px 0 24px;
}

.hero h1 {
  font-size: 36px;
  margin: 0 0 12px;
  border: 0;
  padding: 0;
}

.hero p.tagline {
  color: var(--muted);
  font-size: 16px;
  margin: 0 0 24px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin: 24px 0;
}

.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}

.card h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.card p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}