/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ── Theme ── */
:root {
  --font-serif: Georgia, "Palatino Linotype", "Book Antiqua", Palatino, serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

[data-theme="dark"] {
  --bg: #0b0d12;
  --bg-surface: #13161e;
  --text: #b0b8c4;
  --text-heading: #d8e0ea;
  --text-muted: #505a68;
  --accent: #4a9a8a;
  --accent-hover: #5fb8a6;
  --accent-glow: rgba(74, 154, 138, 0.15);
  --border: #1a1e28;
  --toggle-icon: "\2600";
  --stars: url('../images/stars-dark.svg');
}

[data-theme="light"] {
  --bg: #f5f3ef;
  --bg-surface: #eae7e1;
  --text: #2c2e33;
  --text-heading: #111318;
  --text-muted: #6e7280;
  --accent: #2d7a6b;
  --accent-hover: #1d5e52;
  --accent-glow: rgba(45, 122, 107, 0.1);
  --border: #d0cdc6;
  --toggle-icon: "\25CF";
  --stars: url('../images/stars-light.svg');
}

/* ── Base ── */
html {
  font-size: 19px;
  line-height: 1.8;
  background: var(--bg) var(--stars) repeat;
  background-size: 600px 600px;
  color: var(--text);
  font-family: var(--font-serif);
  -webkit-font-smoothing: antialiased;
}

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

/* ── Layout ── */
.container {
  max-width: 620px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

/* ── Header ── */
.site-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 3rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.site-title {
  font-size: 0.9rem;
  font-weight: normal;
  color: var(--text-muted);
  font-family: var(--font-sans);
  letter-spacing: 0.05em;
}
.site-title:hover {
  color: var(--accent);
}

nav {
  display: flex;
  align-items: center;
  gap: 1rem;
  font-family: var(--font-sans);
  font-size: 0.85rem;
}

nav a {
  color: var(--text-muted);
}
nav a:hover {
  color: var(--text-heading);
}

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 0.85rem;
  color: var(--text-muted);
  padding: 0;
  line-height: 1;
}
.theme-toggle:hover {
  color: var(--text-heading);
}
.theme-icon::after {
  content: var(--toggle-icon);
}

/* ── Landing ── */
.landing {
  padding: 4rem 0 2rem;
}

.landing-header {
  text-align: center;
  margin-bottom: 3.5rem;
  position: relative;
}

.landing-header::before {
  content: '';
  position: absolute;
  top: -8rem;
  left: 50%;
  transform: translateX(-50%);
  width: 400px;
  height: 400px;
  background: radial-gradient(ellipse, var(--accent-glow) 0%, transparent 70%);
  pointer-events: none;
  z-index: -1;
}

.landing-title {
  font-size: 2.6rem;
  font-weight: normal;
  color: var(--text-heading);
  letter-spacing: 0.02em;
  line-height: 1.2;
  margin-bottom: 0.8rem;
}

.landing-subtitle {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  color: var(--text-muted);
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

/* ── Prologue ── */
.prologue p {
  margin-bottom: 1.4rem;
}

.prologue .section-break {
  text-align: center;
  color: var(--text-muted);
  margin: 2.5rem 0;
  font-size: 0.9rem;
  letter-spacing: 0.4em;
}

.prologue .turn {
  text-align: center;
  font-style: italic;
  color: var(--text-heading);
  margin: 2.5rem 0;
}

.prologue .signal {
  text-align: center;
  font-family: var(--font-mono);
  font-size: 1.4rem;
  color: var(--accent);
  letter-spacing: 0.25em;
  margin: 2.5rem 0;
}

.prologue .closing {
  text-align: center;
  color: var(--text-heading);
  font-style: italic;
}

/* ── Chapters ── */
.chapter-header {
  margin-bottom: 2.5rem;
  text-align: center;
}

.chapter-number {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  color: var(--text-muted);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  display: block;
  margin-bottom: 0.5rem;
}

.chapter-title {
  font-size: 2rem;
  font-weight: normal;
  color: var(--text-heading);
  line-height: 1.3;
}

.chapter-content p {
  margin-bottom: 1.4rem;
}

.chapter-content blockquote {
  border-left: 2px solid var(--accent);
  padding-left: 1rem;
  color: var(--text-muted);
  margin: 1.5rem 0;
  font-style: italic;
}

.chapter-content hr {
  border: none;
  text-align: center;
  margin: 2.5rem 0;
}
.chapter-content hr::after {
  content: '\00B7  \00B7  \00B7';
  color: var(--text-muted);
  letter-spacing: 0.3em;
}

.chapter-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-family: var(--font-sans);
  font-size: 0.85rem;
}

.chapter-nav a {
  color: var(--text-muted);
}
.chapter-nav a:hover {
  color: var(--accent);
}

/* ── Page ── */
.page h1 {
  font-size: 2rem;
  font-weight: normal;
  color: var(--text-heading);
  margin-bottom: 1.5rem;
}

.page h2 {
  font-size: 1.3rem;
  color: var(--text-heading);
  margin: 2rem 0 0.8rem;
}

.page p {
  margin-bottom: 1.2rem;
}

/* ── AI additions ── */
.ai-addition {
  text-decoration: underline dotted var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  cursor: help;
}

/* ── Page lists ── */
.page ul, .page ol {
  margin: 0 0 1.2rem 1.2rem;
}

.page li {
  margin-bottom: 0.3rem;
}

.page a {
  color: var(--accent);
}

.page hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 2rem 0;
}

.page em {
  color: var(--text-muted);
}

/* ── Footer ── */
.site-footer {
  margin-top: 4rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  color: var(--text-muted);
  text-align: center;
  display: flex;
  justify-content: center;
  gap: 1rem;
}

.footer-links a {
  color: var(--text-muted);
}
.footer-links a:hover {
  color: var(--accent);
}

/* ── 404 ── */
.error-page {
  text-align: center;
  padding: 4rem 0;
}

.error-page h1 {
  font-size: 3rem;
  color: var(--text-heading);
  margin-bottom: 0.5rem;
}

.error-page p {
  margin-bottom: 1rem;
  color: var(--text-muted);
}

/* ── Responsive ── */
@media (max-width: 640px) {
  html {
    font-size: 17px;
  }

  .landing {
    padding: 2rem 0 1rem;
  }

  .landing-title {
    font-size: 2rem;
  }

  .landing-header::before {
    width: 280px;
    height: 280px;
  }

  .chapter-title {
    font-size: 1.6rem;
  }
}