/* ============================================================
   THE FREQUENCY BELOW — Chapter Reading Styles
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:ital,wght@0,400;0,600;0,700;1,400;1,700&family=Inter:wght@300;400;500;600&family=Space+Mono:ital@0;1&display=swap');

/* ── ROOT & TOKENS ────────────────────────────────────────── */
:root {
  --bg:       #07070f;
  --bg-2:     #0d0d1a;
  --bg-3:     #121222;

  --text:     #e4e0da;
  --text-dim: #8a8696;
  --text-muted: #4a475c;

  --border:       rgba(255, 255, 255, 0.06);
  --border-hover: rgba(255, 255, 255, 0.13);

  /* Part 1 palette — the hearing world's constraint */
  --p1:        hsl(215, 50%, 58%);
  --p1-dim:    hsla(215, 50%, 58%, 0.08);
  --p1-border: hsla(215, 50%, 58%, 0.28);
  --p1-glow:   hsla(215, 70%, 55%, 0.10);

  /* Accent: amber/gold for wave and key lines */
  --accent:     hsl(38, 72%, 58%);
  --accent-dim: hsla(38, 72%, 58%, 0.08);
  --accent-border: hsla(38, 72%, 58%, 0.25);

  --font-display: 'Playfair Display', Georgia, serif;
  --font-ui:      'Inter', system-ui, sans-serif;
  --font-mono:    'Space Mono', 'Courier New', monospace;

  --col-prose: 660px;
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --transition: 0.28s var(--ease);
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-display);
  line-height: 1;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* ============================================================
   PROGRESS BAR
   ============================================================ */
#progressBar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--p1);
  transform: scaleX(0);
  transform-origin: left;
  z-index: 1000;
  pointer-events: none;
}

/* ============================================================
   NAVIGATION
   ============================================================ */
.chapter-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 52px;
  padding: 0 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(7, 7, 15, 0.88);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  z-index: 200;
}

.nav-back {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-family: var(--font-mono);
  font-size: 0.63rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-muted);
  text-decoration: none;
  transition: color var(--transition);
}
.nav-back:hover { color: var(--p1); }
.nav-back svg {
  width: 13px;
  height: 13px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex-shrink: 0;
}

.nav-center {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  font-family: var(--font-display);
  font-size: 0.88rem;
  font-style: italic;
  color: var(--text-muted);
  pointer-events: none;
  white-space: nowrap;
}

.nav-meta {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.nav-chapter-tag {
  padding: 0.2rem 0.55rem;
  border: 1px solid var(--p1-border);
  border-radius: 3px;
  color: var(--p1);
  font-size: 0.58rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

/* ============================================================
   CHAPTER HEADER
   ============================================================ */
.chapter-header {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 8rem 2rem 5rem;
  overflow: hidden;
  border-bottom: 1px solid var(--border);
}

.chapter-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 50% 60%, hsla(215, 55%, 35%, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.chapter-header__canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.chapter-header__content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: var(--col-prose);
  width: 100%;
}

.chapter-header__eyebrow {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--p1);
  opacity: 0.7;
  margin-bottom: 2.5rem;
  animation: fadeUp 0.9s var(--ease) 0.1s both;
}

.chapter-header__number {
  font-family: var(--font-ui);
  font-size: clamp(7rem, 20vw, 14rem);
  font-weight: 600;
  line-height: 0.88;
  color: transparent;
  -webkit-text-stroke: 1px hsla(215, 50%, 58%, 0.12);
  letter-spacing: -0.04em;
  margin-bottom: -1.5rem;
  animation: fadeUp 0.9s var(--ease) 0.2s both;
  user-select: none;
}

.chapter-header__title {
  font-family: var(--font-display);
  font-size: clamp(2.75rem, 7vw, 5rem);
  font-weight: 700;
  font-style: italic;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--text);
  margin-bottom: 1.5rem;
  animation: fadeUp 0.9s var(--ease) 0.35s both;
}

.chapter-header__motif {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 4rem;
  animation: fadeUp 0.9s var(--ease) 0.5s both;
}

.chapter-header__scroll {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.65rem;
  animation: fadeUp 0.9s var(--ease) 0.8s both;
}
.chapter-header__scroll span {
  font-family: var(--font-mono);
  font-size: 0.58rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.chapter-header__scroll-line {
  width: 1px;
  height: 52px;
  background: linear-gradient(to bottom, var(--p1-border), transparent);
  animation: scrollPulse 2.4s ease-in-out 1.4s infinite;
  transform-origin: top;
}

/* ============================================================
   PROSE COLUMN
   ============================================================ */
.chapter-prose {
  max-width: var(--col-prose);
  margin: 0 auto;
  padding: 7rem 2rem 8rem;
}

/* Scene containers */
.scene { margin-bottom: 0; }

/* Paragraphs */
.chapter-prose p {
  font-family: var(--font-display);
  font-size: clamp(1.06rem, 1.6vw, 1.175rem);
  line-height: 1.95;
  color: var(--text-dim);
  margin-bottom: 1.75em;
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.65s var(--ease), transform 0.65s var(--ease);
}
.chapter-prose p.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Emphasis within prose */
.chapter-prose em {
  font-style: italic;
  color: var(--text);
}

/* Drop cap on opening paragraph */
.scene:first-child p:first-child::first-letter {
  font-family: var(--font-display);
  font-size: 5em;
  font-weight: 700;
  float: left;
  line-height: 0.74;
  margin-right: 0.08em;
  margin-top: 0.05em;
  color: var(--p1);
}

/* Key lines (italicized standalone beats) */
.prose-aside {
  display: block;
  font-style: italic;
  font-size: 1em;
  color: var(--text-muted);
  border-left: 2px solid var(--p1-border);
  padding: 0.1rem 0 0.1rem 1.5rem;
  margin: 2.5rem 0;
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.65s var(--ease), transform 0.65s var(--ease);
}
.prose-aside.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   SECTION BREAKS
   ============================================================ */
.section-break {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  margin: 3.5rem 0;
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.65s var(--ease), transform 0.65s var(--ease);
}
.section-break.visible {
  opacity: 1;
  transform: translateY(0);
}
.section-break::before,
.section-break::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}
.section-break span {
  color: var(--p1);
  font-size: 0.75rem;
  opacity: 0.5;
}

/* ============================================================
   CHAPTER FOOTER
   ============================================================ */
.chapter-footer {
  border-top: 1px solid var(--border);
  padding: 4rem 2rem;
  max-width: var(--col-prose);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
}

.footer-book-info { flex: 1; }
.footer-book-info strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-style: italic;
  font-weight: 400;
  color: var(--text-dim);
  margin-bottom: 0.35rem;
}
.footer-book-info span {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.footer-nav {
  display: flex;
  gap: 0.75rem;
  align-items: center;
}

.footer-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  text-decoration: none;
  padding: 0.55rem 1.1rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  transition: color var(--transition), border-color var(--transition), background var(--transition);
}
.footer-link:hover {
  color: var(--p1);
  border-color: var(--p1-border);
  background: var(--p1-dim);
}
.footer-link.is-disabled {
  opacity: 0.3;
  pointer-events: none;
}
.footer-link svg {
  width: 12px;
  height: 12px;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* ── Site footer ─────────────────────────────────────────── */
.site-footer {
  padding: 2.5rem;
  border-top: 1px solid var(--border);
  text-align: center;
}
.site-footer p {
  font-family: var(--font-mono);
  font-size: 0.58rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-muted);
}

/* ============================================================
   ANIMATIONS
   ============================================================ */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes scrollPulse {
  0%, 100% { opacity: 0.2; transform: scaleY(0.88); }
  50%       { opacity: 0.8; transform: scaleY(1.1); }
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 720px) {
  .chapter-nav { padding: 0 1.25rem; }
  .nav-center { display: none; }
  .chapter-prose { padding: 5rem 1.5rem 6rem; }
  .chapter-footer { padding: 3rem 1.5rem; flex-direction: column; align-items: flex-start; }
}

@media (max-width: 480px) {
  .chapter-header { padding: 7rem 1.5rem 4rem; }
  .chapter-header__number { font-size: clamp(5rem, 22vw, 7rem); }
}