:root {
  --ink: #0b1220;
  --background: #f8fafc;
  --surface: #ffffff;
  --muted: #6b7280;
  --border: #e5e7eb;
  --accent: #d6a84f;
  --green: #16a34a;
  --max-width: 720px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 17px;
  line-height: 1.65;
  color: var(--ink);
  background: var(--background);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--ink);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover {
  color: #1f2937;
}

.site-header {
  background: var(--ink);
  color: #fff;
  padding: 1.25rem 1.5rem;
}

.site-header a {
  color: #fff;
  text-decoration: none;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.site-header span {
  color: #94a3b8;
  font-weight: 500;
  font-size: 0.95rem;
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2.5rem 1.5rem 4rem;
}

h1 {
  font-size: clamp(1.85rem, 4vw, 2.35rem);
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin: 0 0 0.75rem;
}

.lead {
  font-size: 1.1rem;
  color: var(--muted);
  margin: 0 0 2rem;
}

.summary-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 12px;
  padding: 1.25rem 1.35rem;
  margin: 0 0 2rem;
  box-shadow: 0 1px 2px rgba(11, 18, 32, 0.04);
}

.summary-box h2 {
  margin: 0 0 0.75rem;
  font-size: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

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

.summary-box li {
  margin-bottom: 0.45rem;
}

.summary-box li:last-child {
  margin-bottom: 0;
}

.toc {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.25rem 1.35rem;
  margin: 0 0 2.5rem;
}

.toc h2 {
  margin: 0 0 0.75rem;
  font-size: 1rem;
}

.toc ol {
  margin: 0;
  padding-left: 1.25rem;
}

.toc li {
  margin-bottom: 0.35rem;
}

.toc a {
  text-decoration: none;
  font-weight: 600;
}

.toc a:hover {
  text-decoration: underline;
}

section {
  margin-bottom: 2.25rem;
}

section h2 {
  font-size: 1.35rem;
  letter-spacing: -0.02em;
  margin: 0 0 0.75rem;
  padding-top: 0.5rem;
}

section h3 {
  font-size: 1.05rem;
  margin: 1.25rem 0 0.5rem;
}

p {
  margin: 0 0 1rem;
}

ul,
ol {
  margin: 0 0 1rem;
  padding-left: 1.25rem;
}

li {
  margin-bottom: 0.4rem;
}

.tag {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--green);
  background: #dcfce7;
  border-radius: 999px;
  padding: 0.2rem 0.55rem;
  margin-left: 0.35rem;
  vertical-align: middle;
}

.note {
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  border-radius: 10px;
  padding: 1rem 1.1rem;
  font-size: 0.95rem;
  margin: 1rem 0;
}

.disclaimer {
  font-size: 0.95rem;
  color: var(--muted);
}

.meta {
  font-size: 0.9rem;
  color: var(--muted);
  margin-bottom: 2rem;
}

.footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem 3rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.footer a {
  color: var(--muted);
}

.hero-cta {
  display: inline-block;
  margin-top: 1rem;
  background: var(--ink);
  color: #fff !important;
  text-decoration: none;
  font-weight: 700;
  padding: 0.85rem 1.25rem;
  border-radius: 999px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #0e1117;
    --surface: #151a23;
    --border: #2a3140;
    --muted: #9ca3af;
  }

  body {
    color: #f3f4f6;
  }

  a {
    color: #e5e7eb;
  }

  .summary-box,
  .toc {
    box-shadow: none;
  }

  .note {
    background: #1e293b;
    border-color: #334155;
  }

  .tag {
    background: #14532d;
    color: #86efac;
  }
}