:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --bg-color: #fafaf9;
  --card-bg: #ffffff;
  --text-color: #292524;
  --text-muted: #78716c;
  --primary-color: #1b4332; /* Deep forest green */
  --primary-hover: #2d6a4f;
  --border-color: #e7e5e4;
  --alert-bg: #fffbeb;
  --alert-border: #f59e0b;
  --alert-text: #b45309;
  --shadow: 0 1px 3px rgba(0,0,0,0.05), 0 1px 2px rgba(0,0,0,0.1);
  --radius: 12px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #0c0a09;
    --card-bg: #1c1917;
    --text-color: #e7e5e4;
    --text-muted: #a8a29e;
    --primary-color: #52b788; /* Bright green accent in dark mode */
    --primary-hover: #74c69d;
    --border-color: #2e2a28;
    --alert-bg: #1c150c;
    --alert-border: #d97706;
    --alert-text: #f59e0b;
  }
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  margin: 0;
  padding: 2rem 1.25rem;
  display: flex;
  justify-content: center;
}

.container {
  max-width: 720px;
  width: 100%;
}

.header {
  text-align: center;
  margin-bottom: 2.5rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border-color);
}

.logo-container {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: var(--primary-color);
  color: var(--bg-color);
  width: 54px;
  height: 54px;
  border-radius: 50%;
  font-weight: 800;
  font-size: 1.6rem;
  margin-bottom: 1rem;
}

.header h1 {
  font-size: 2rem;
  font-weight: 800;
  margin: 0 0 0.5rem 0;
  color: var(--text-color);
  letter-spacing: -0.025em;
}

.header p {
  color: var(--text-muted);
  margin: 0;
  font-size: 0.95rem;
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 2.5rem;
  box-shadow: var(--shadow);
  margin-bottom: 2rem;
}

@media (max-width: 600px) {
  .card {
    padding: 1.5rem;
  }
}

.toc-card {
  padding: 1.5rem 2rem;
  margin-bottom: 2rem;
}

.toc-card h2 {
  font-size: 0.9rem;
  margin-top: 0;
  margin-bottom: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  border-bottom: none;
  padding-bottom: 0;
}

.toc-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.5rem;
}

@media (min-width: 600px) {
  .toc-list {
    grid-template-columns: 1fr 1fr;
  }
}

.toc-list a {
  color: var(--primary-color);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
}

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

h2 {
  font-size: 1.35rem;
  font-weight: 700;
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  color: var(--text-color);
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.5rem;
}

h2:first-of-type {
  margin-top: 0;
}

h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
  color: var(--text-color);
}

p, li {
  font-size: 0.95rem;
  color: var(--text-color);
}

li {
  margin-bottom: 0.5rem;
}

ul {
  padding-left: 1.5rem;
}

.alert {
  background-color: var(--alert-bg);
  border-left: 4px solid var(--alert-border);
  color: var(--alert-text);
  padding: 1.25rem;
  border-radius: 6px;
  margin: 1.5rem 0;
  font-size: 0.9rem;
}

.alert h4 {
  margin: 0 0 0.5rem 0;
  font-weight: 700;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.alert p {
  margin: 0;
  color: inherit;
  line-height: 1.5;
}

a {
  color: var(--primary-color);
  text-decoration: underline;
}

a:hover {
  color: var(--primary-hover);
}

.footer {
  text-align: center;
  padding: 2rem 0;
  color: var(--text-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border-color);
  margin-top: 4rem;
}