/* FOSM Book — Stylesheet */
:root {
  --aztec-purple: #7147FF;
  --midnight-blue: #000032;
  --papaya-orange: #EE5F19;
  --bg: #fafaf9;
  --text: #1a1a1a;
  --code-bg: #f4f4f5;
  --border: #e4e4e7;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: "Georgia", "Times New Roman", serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.75;
  max-width: 48rem;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

.site-nav {
  border-bottom: 2px solid var(--midnight-blue);
  padding-bottom: 0.75rem;
  margin-bottom: 2.5rem;
}
.site-nav .brand {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--aztec-purple);
  text-decoration: none;
  letter-spacing: 0.05em;
}
.site-nav .subtitle {
  display: block;
  font-size: 0.85rem;
  color: #666;
}

h1, h2, h3, h4 { font-family: "Helvetica Neue", Arial, sans-serif; color: var(--midnight-blue); }
h1 { font-size: 2rem; margin: 1.5rem 0 1rem; }
h2 { font-size: 1.5rem; margin: 2rem 0 0.75rem; border-bottom: 1px solid var(--border); padding-bottom: 0.3rem; }
h3 { font-size: 1.2rem; margin: 1.5rem 0 0.5rem; }

p { margin: 0.75rem 0; }
a { color: var(--aztec-purple); }

code {
  font-family: "SF Mono", "Fira Code", monospace;
  font-size: 0.88em;
  background: var(--code-bg);
  padding: 0.15em 0.35em;
  border-radius: 3px;
}

pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1rem 0;
  line-height: 1.5;
}
pre code { background: none; padding: 0; }

blockquote {
  border-left: 4px solid var(--aztec-purple);
  padding: 0.75rem 1.25rem;
  margin: 1.25rem 0;
  background: #f0ecff;
  border-radius: 0 6px 6px 0;
}

table { width: 100%; border-collapse: collapse; margin: 1rem 0; }
th, td { border: 1px solid var(--border); padding: 0.5rem 0.75rem; text-align: left; }
th { background: var(--midnight-blue); color: white; font-family: "Helvetica Neue", Arial, sans-serif; }

.chapter-header { margin-bottom: 2rem; }
.part-label {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--papaya-orange);
  margin-bottom: 0.25rem;
}
.chapter-number {
  display: block;
  font-size: 0.9rem;
  font-weight: 400;
  color: var(--aztec-purple);
  margin-bottom: 0.15rem;
}

.chapter-summary {
  background: #fff7ed;
  border: 1px solid #fed7aa;
  border-radius: 8px;
  padding: 1.25rem 1.5rem;
  margin-top: 3rem;
}
.chapter-summary h3 { color: var(--papaya-orange); margin-top: 0; }
.chapter-summary ul { padding-left: 1.25rem; }
.chapter-summary li { margin: 0.3rem 0; }

/* Callout boxes */
.callout {
  border-radius: 8px;
  padding: 1rem 1.25rem;
  margin: 1.25rem 0;
}
.callout-why { background: #eff6ff; border-left: 4px solid #3b82f6; }
.callout-hood { background: #f0fdf4; border-left: 4px solid #22c55e; }
.callout-ai { background: #faf5ff; border-left: 4px solid var(--aztec-purple); }
.callout strong:first-child { display: block; margin-bottom: 0.3rem; }

/* Listing labels */
.listing-label {
  font-family: "Helvetica Neue", Arial, sans-serif;
  font-size: 0.8rem;
  font-weight: 700;
  color: #666;
  margin-bottom: 0.25rem;
}

footer {
  margin-top: 4rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: #888;
}

/* Collapsible Table of Contents */
.chapter-toc {
  margin: 0 0 2rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fafafa;
}
.chapter-toc details {
  padding: 0;
}
.chapter-toc summary {
  font-family: "Helvetica Neue", Arial, sans-serif;
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--midnight-blue);
  cursor: pointer;
  padding: 0.75rem 1.25rem;
  user-select: none;
  list-style: none;
}
.chapter-toc summary::before {
  content: "\25B6\FE0E";
  display: inline-block;
  margin-right: 0.5rem;
  font-size: 0.7rem;
  transition: transform 0.2s;
}
.chapter-toc details[open] summary::before {
  transform: rotate(90deg);
}
.chapter-toc summary::-webkit-details-marker { display: none; }
.chapter-toc ol {
  padding: 0 1.25rem 0.75rem 2.5rem;
  margin: 0;
}
.chapter-toc li {
  margin: 0.2rem 0;
  font-size: 0.9rem;
  line-height: 1.5;
}
.chapter-toc li a {
  text-decoration: none;
  color: var(--text);
}
.chapter-toc li a:hover {
  color: var(--aztec-purple);
}
.toc-level-3 { font-size: 0.85rem; color: #555; }

/* Prev / Next Chapter Navigation */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 2px solid var(--border);
}
.chapter-nav-prev,
.chapter-nav-next {
  display: flex;
  flex-direction: column;
  text-decoration: none;
  max-width: 40%;
  padding: 0.75rem 1rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  transition: border-color 0.15s, background 0.15s;
}
.chapter-nav-prev:hover,
.chapter-nav-next:hover {
  border-color: var(--aztec-purple);
  background: #f8f6ff;
}
.chapter-nav-next { text-align: right; margin-left: auto; }
.chapter-nav-label {
  font-family: "Helvetica Neue", Arial, sans-serif;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--aztec-purple);
}
.chapter-nav-title {
  font-size: 0.9rem;
  color: var(--text);
  margin-top: 0.15rem;
}
.chapter-nav-toc-link {
  font-size: 0.8rem;
  align-self: center;
  color: #888;
  text-decoration: none;
}
.chapter-nav-toc-link:hover { color: var(--aztec-purple); }
.chapter-nav-disabled { visibility: hidden; }

@media (max-width: 640px) {
  .chapter-nav { flex-direction: column; }
  .chapter-nav-prev,
  .chapter-nav-next { max-width: 100%; }
  .chapter-nav-next { text-align: left; margin-left: 0; }
  .chapter-nav-toc-link { order: -1; }
}

/* Mermaid diagrams */
.mermaid { margin: 1.5rem 0; text-align: center; }