/* ==========================================================================
   kaguya.dev — vol. 17 — Phase-Locked Sonar Returns
   dark-academia drowned at three thousand metres
   palette: ocean-deep · type: tech-mono + dark-academia serif
   ========================================================================== */

:root {
  --hadal-ink:        #04121f;  /* page background — the deepest void */
  --abyssal-navy:     #0a2540;  /* primary structural surface */
  --bathyal-blue:     #0e3a5f;  /* secondary surface — banding stripes */
  --biolum-cyan:      #1f6f8b;  /* interactive accents, link underlines */
  --foam-memory:      #9ec7d9;  /* body prose at full reading brightness */
  --pearl-mist:       #cfd6dc;  /* default body text on dark ground */
  --candle-vellum:    #f4ecd2;  /* display titles & chapter glyphs (the warm dot) */
  --drowned-stone:    #7a8a96;  /* muted UI, marginalia secondary */
  --oxblood:          #3a1f1a;  /* the librarian's red ink — errata only */

  --mono:    "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --serif:   "Cormorant Garamond", "Iowan Old Style", Georgia, serif;
  --margin-mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;

  --gauge-w: 56px;
}

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

html { scroll-behavior: smooth; }

body {
  background-color: var(--abyssal-navy);   /* JS interpolates surface→hadal */
  color: var(--pearl-mist);
  font-family: var(--serif);
  font-size: 1.075rem;
  line-height: 1.78;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  position: relative;
}

/* ---- marine-snow canvas overlay ------------------------------------------ */
#marine-snow {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 1;
  opacity: 0.55;
}

/* ---- depth gauge column -------------------------------------------------- */
#depth-gauge {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: var(--gauge-w);
  z-index: 6;
  background: linear-gradient(180deg,
              rgba(10,37,64,0.0) 0%,
              rgba(10,37,64,0.55) 8%,
              rgba(4,18,31,0.65) 92%,
              rgba(4,18,31,0.0) 100%);
  border-right: 1px solid rgba(31,111,139,0.35);
  font-family: var(--mono);
  font-feature-settings: "tnum" 1, "lnum" 1;
}
.dg-track {
  position: absolute;
  left: 50%;
  top: 4.5rem; bottom: 4.5rem;
  width: 1px;
  transform: translateX(-50%);
  background-image:
    linear-gradient(180deg, rgba(122,138,150,0.45) 0%, rgba(122,138,150,0.10) 100%);
}
/* tick marks every 100px of gauge height — drawn with repeating gradient */
.dg-track::before {
  content: "";
  position: absolute;
  left: -3px; right: -3px; top: 0; bottom: 0;
  background-image: repeating-linear-gradient(
    180deg,
    rgba(122,138,150,0.40) 0px,
    rgba(122,138,150,0.40) 1px,
    transparent 1px,
    transparent 56px
  );
}
.dg-indicator {
  position: absolute;
  left: 8px; right: 8px;
  top: 4.5rem;
  height: 1px;
  background: var(--biolum-cyan);
  box-shadow: 0 0 6px 1px rgba(31,111,139,0.7);
  transition: top 0.12s linear;
}
.dg-readout {
  position: absolute;
  left: 50%;
  bottom: 1.6rem;
  transform: translateX(-50%) rotate(-90deg);
  transform-origin: center;
  white-space: nowrap;
  font-size: 0.92rem;
  letter-spacing: 0.06em;
  color: var(--foam-memory);
}
.dg-readout #dg-digits {
  color: var(--candle-vellum);
}
.dg-readout #dg-digits .lit {
  color: var(--biolum-cyan);
  text-shadow: 0 0 5px rgba(31,111,139,0.9);
}
.dg-unit { color: var(--drowned-stone); margin-left: 0.15em; }
.dg-label {
  position: absolute;
  left: 50%;
  top: 1.4rem;
  transform: translateX(-50%) rotate(-90deg);
  transform-origin: center;
  font-size: 0.6rem;
  letter-spacing: 0.4em;
  text-transform: uppercase;
  color: var(--drowned-stone);
}

/* ==========================================================================
   BREATHING FRAME — the signature border-animate motif
   ========================================================================== */
.breathing-frame {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 2;
  overflow: visible;
}
.breathing-frame rect {
  fill: none;
  stroke: var(--biolum-cyan);
  stroke-width: 0.18;
  stroke-dasharray: 1.6 1.2;
  vector-effect: non-scaling-stroke;
  animation: breathe 16s ease-in-out infinite alternate;
}
@keyframes breathe {
  from { stroke-dashoffset: 0; opacity: 0.55; }
  to   { stroke-dashoffset: 28; opacity: 0.85; }
}
/* the hero frame is the largest, brightest version */
.hero .breathing-frame rect {
  stroke-width: 0.22;
  stroke: var(--biolum-cyan);
}
.frame-h2 rect {
  stroke-dasharray: 1.2 1.0;
  opacity: 0.6;
}

/* ==========================================================================
   HERO — the sealed chamber
   ========================================================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background:
    radial-gradient(ellipse at 50% 38.2%, rgba(14,58,95,0.45) 0%, rgba(10,37,64,0) 60%),
    var(--abyssal-navy);
  padding: 4rem var(--gauge-w);
  overflow: hidden;
}
/* faint phosphor scanline glow over the hero */
.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: repeating-linear-gradient(
    180deg, rgba(255,255,255,0.012) 0px, rgba(255,255,255,0.012) 1px,
    transparent 1px, transparent 3px);
  mix-blend-mode: screen;
  z-index: 3;
}
.hero-inner {
  position: relative;
  z-index: 4;
  max-width: 64ch;
  text-align: center;
  /* push content toward the golden-ratio lower band */
  transform: translateY(min(8vh, 5rem));
}
.hero-kicker {
  font-family: var(--margin-mono);
  font-size: 0.72rem;
  letter-spacing: 0.42em;
  text-transform: uppercase;
  color: var(--drowned-stone);
  margin-bottom: 2.2rem;
}
.hero-title {
  font-family: var(--mono);
  font-weight: 500;
  font-size: clamp(2.4rem, 5.5vw, 5.2rem);
  letter-spacing: -0.01em;
  line-height: 1.12;
  color: var(--candle-vellum);
  margin-bottom: 1.8rem;
  text-wrap: balance;
}
.hero-title .sep { color: var(--drowned-stone); font-weight: 400; }
.hero-title .emdash { color: var(--biolum-cyan); font-weight: 400; }
.hero-abstract {
  font-family: var(--serif);
  font-style: italic;
  font-weight: 400;
  font-size: 1.18rem;
  line-height: 1.7;
  color: var(--foam-memory);
  max-width: 54ch;
  margin: 0 auto 2.2rem;
  text-align: justify;
  text-align-last: center;
}
.hero-meta {
  font-family: var(--margin-mono);
  font-size: 0.74rem;
  letter-spacing: 0.12em;
  color: var(--drowned-stone);
}
.hero-meta .dot { margin: 0 0.7em; color: var(--biolum-cyan); }
.hero-scrollcue {
  margin-top: 3.4rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.7rem;
  font-family: var(--margin-mono);
  font-size: 0.66rem;
  letter-spacing: 0.4em;
  text-transform: uppercase;
  color: var(--drowned-stone);
}
.cue-arrow {
  font-size: 1rem;
  letter-spacing: 0;
  color: var(--biolum-cyan);
  animation: cuedrift 3.6s ease-in-out infinite;
}
@keyframes cuedrift {
  0%,100% { transform: translateY(0); opacity: 0.5; }
  50%     { transform: translateY(6px); opacity: 1; }
}

/* ==========================================================================
   CHRONICLE — the vertical manuscript
   ========================================================================== */
.chronicle {
  position: relative;
  z-index: 4;
  padding-left: var(--gauge-w);
  padding-bottom: 6rem;
}

.chapter {
  position: relative;
  padding: 5.5rem 2rem 4rem;
}
/* alternating chapter banding stripes (bathyal blue) */
.chapter[data-depth-band="1"],
.chapter[data-depth-band="3"] {
  background: linear-gradient(180deg,
              rgba(14,58,95,0.0) 0%,
              rgba(14,58,95,0.16) 50%,
              rgba(14,58,95,0.0) 100%);
}

/* ---- chapter rule (animates from centre outward) ------------------------- */
.chapter-rule {
  --rule-extent: 0%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.2rem;
  margin-bottom: 3.5rem;
}
.rule-line {
  height: 1px;
  width: var(--rule-extent);
  max-width: 36ch;
  background: linear-gradient(90deg, rgba(31,111,139,0) 0%, rgba(31,111,139,0.8) 100%);
  transition: width 1.4s ease-out;
}
.rule-line.rule-right {
  background: linear-gradient(90deg, rgba(31,111,139,0.8) 0%, rgba(31,111,139,0) 100%);
}
.chapter-glyph {
  flex: 0 0 auto;
  width: 28px;
  height: 28px;
  display: inline-block;
  background-repeat: no-repeat;
  background-position: center;
  background-size: contain;
  opacity: 0.92;
}
/* eight single-stroke vellum glyphs, drawn inline as data-URI SVGs */
.chapter-glyph[data-glyph="0"] { /* sonar ping */
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><g fill="none" stroke="%23f4ecd2" stroke-width="1.3" stroke-linecap="round"><circle cx="16" cy="16" r="2.2"/><path d="M16 14 V4"/><path d="M11 11 A7 7 0 0 1 21 11"/><path d="M8 8 A11.5 11.5 0 0 1 24 8"/></g></svg>');
}
.chapter-glyph[data-glyph="1"] { /* fish skeleton */
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><g fill="none" stroke="%23f4ecd2" stroke-width="1.3" stroke-linecap="round"><path d="M5 16 L24 16"/><path d="M24 16 L29 11 M24 16 L29 21"/><circle cx="7" cy="16" r="2.2"/><path d="M11 12 V20 M15 11 V21 M19 12 V20"/></g></svg>');
}
.chapter-glyph[data-glyph="2"] { /* sextant arc */
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><g fill="none" stroke="%23f4ecd2" stroke-width="1.3" stroke-linecap="round"><path d="M6 26 L26 26"/><path d="M6 26 A20 20 0 0 1 26 26"/><path d="M6 26 L20 14"/><circle cx="6" cy="26" r="1.6"/></g></svg>');
}
.chapter-glyph[data-glyph="3"] { /* depth-gauge dial */
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><g fill="none" stroke="%23f4ecd2" stroke-width="1.3" stroke-linecap="round"><circle cx="16" cy="16" r="11"/><path d="M16 16 L22 9"/><path d="M16 5 V8 M27 16 H24 M16 27 V24 M5 16 H8"/></g></svg>');
}
.chapter-glyph[data-glyph="4"] { /* anchor */
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32"><g fill="none" stroke="%23f4ecd2" stroke-width="1.3" stroke-linecap="round"><circle cx="16" cy="7" r="2.4"/><path d="M16 9 V25"/><path d="M10 14 H22"/><path d="M16 25 A9 9 0 0 1 7 17 M16 25 A9 9 0 0 0 25 17"/><path d="M7 17 L5 19 M25 17 L27 19"/></g></svg>');
}
/* glyphs cycle past 5 via JS modulo, but only 5 chapters exist */

.chapter-num {
  font-family: var(--margin-mono);
  font-size: 0.72rem;
  letter-spacing: 0.4em;
  text-transform: uppercase;
  color: var(--biolum-cyan);
  text-align: center;
  margin-bottom: 1rem;
}
.chapter-head {
  margin-bottom: 3.5rem;
  text-align: center;
}
.h2-wrap {
  position: relative;
  display: inline-block;
  padding: 1.4rem 2.4rem;
  margin: 0.4rem 0 1.2rem;
}
.chapter-head h2 {
  font-family: var(--mono);
  font-weight: 500;
  font-size: clamp(1.7rem, 3.6vw, 2.8rem);
  letter-spacing: -0.005em;
  line-height: 1.2;
  color: var(--candle-vellum);
}
.chapter-dek {
  font-family: var(--serif);
  font-style: italic;
  font-size: 1.02rem;
  color: var(--drowned-stone);
  max-width: 48ch;
  margin: 0 auto;
}

/* ---- manuscript grid: marginalia | prose -------------------------------- */
.manuscript {
  display: grid;
  grid-template-columns: 18ch 68ch;
  gap: 3rem;
  justify-content: center;
  align-items: start;
}
.prose { grid-column: 2; }
.prose p {
  color: var(--pearl-mist);
  margin-bottom: 1.5rem;
  text-align: justify;
  hyphens: auto;
}
.prose p.lead {
  font-size: 1.18rem;
  line-height: 1.72;
  color: var(--foam-memory);
}
.prose p.lead::first-letter {
  font-family: var(--mono);
  font-size: 3.2rem;
  font-weight: 500;
  line-height: 1;
  float: left;
  margin: 0.08em 0.12em 0 0;
  color: var(--candle-vellum);
}
.prose p.closing-line,
.closing-line {
  font-family: var(--margin-mono);
  font-size: 0.82rem;
  letter-spacing: 0.16em;
  color: var(--biolum-cyan);
  text-align: center;
  margin-top: 2.6rem;
}

/* footnote markers in prose: daggers & obeli, JetBrains Mono */
.fn-mark {
  font-family: var(--mono);
  font-size: 0.7em;
  vertical-align: super;
  color: var(--biolum-cyan);
  cursor: pointer;
  padding: 0 0.15em;
  transition: color 0.2s ease, text-shadow 0.2s ease;
}
.fn-mark:hover {
  color: var(--foam-memory);
  text-shadow: 0 0 6px rgba(31,111,139,0.9);
}
.fn-mark.active {
  color: var(--candle-vellum);
  text-shadow: 0 0 7px rgba(31,111,139,1);
}

/* ---- marginalia gutter (desktop) ---------------------------------------- */
.margin-note {
  grid-column: 1;
  position: sticky;
  top: 5rem;
  font-family: var(--margin-mono);
  font-size: 0.78rem;
  line-height: 1.55;
  letter-spacing: 0.02em;
  color: var(--drowned-stone);
  border-left: 1px solid rgba(31,111,139,0.35);
  padding-left: 0.9rem;
  margin-bottom: 2.4rem;
  transition: color 0.3s ease, border-color 0.3s ease;
}
.margin-note .mn-mark {
  display: block;
  font-family: var(--mono);
  color: var(--biolum-cyan);
  font-size: 0.85rem;
  margin-bottom: 0.3rem;
}
.margin-note .mn-body { display: block; }
.margin-note code {
  font-family: var(--margin-mono);
  color: var(--foam-memory);
  background: rgba(14,58,95,0.4);
  padding: 0 0.25em;
}
.margin-note.highlight {
  color: var(--foam-memory);
  border-left-color: var(--biolum-cyan);
}
.margin-note.errata {
  border-left-color: rgba(58,31,26,0.9);
  color: #b08a82;
}
.margin-note.errata .mn-mark {
  color: var(--oxblood);
  background: rgba(58,31,26,0.45);
  color: #c79a90;
  font-family: var(--margin-mono);
  letter-spacing: 0.3em;
  text-transform: uppercase;
  font-size: 0.6rem;
  padding: 0.05em 0.3em;
  display: inline-block;
}

/* ---- code block as submersible instrument ------------------------------- */
.code-block {
  position: relative;
  max-width: 86ch;
  margin: 3rem auto 0;
  border: 1px solid var(--bathyal-blue);
  background: #061a2c;
  box-shadow: inset 0 0 40px rgba(0,0,0,0.5);
}
.cb-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 1rem;
  background: var(--bathyal-blue);
  border-bottom: 1px solid rgba(31,111,139,0.45);
  font-family: var(--margin-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}
.cb-lang { color: var(--foam-memory); }
.cb-lamp {
  font-size: 0.62rem;
  letter-spacing: 0.2em;
  padding: 0.12em 0.5em;
  border: 1px solid currentColor;
  border-radius: 2px;
}
.cb-lamp[data-state="input"]  { color: var(--biolum-cyan); box-shadow: 0 0 6px rgba(31,111,139,0.5); }
.cb-lamp[data-state="output"] { color: var(--candle-vellum); box-shadow: 0 0 6px rgba(244,236,210,0.25); }
.code-block pre {
  position: relative;
  margin: 0;
  padding: 1.2rem 1.4rem;
  overflow-x: auto;
}
.code-block pre::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(rgba(255,255,255,0.02) 50%, transparent 50%);
  background-size: 100% 2px;
}
.code-block code {
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--foam-memory);
  white-space: pre;
  font-feature-settings: "tnum" 1;
}

/* ==========================================================================
   CHRONICLE FOOTER
   ========================================================================== */
.chronicle-foot {
  position: relative;
  max-width: 64ch;
  margin: 6rem auto 0;
  padding: 3.4rem 2.4rem;
  text-align: center;
}
.cf-line {
  font-family: var(--mono);
  font-size: 1.3rem;
  font-weight: 500;
  color: var(--candle-vellum);
  letter-spacing: -0.01em;
  margin-bottom: 1rem;
}
.cf-sub {
  font-family: var(--serif);
  font-style: italic;
  color: var(--foam-memory);
  margin-bottom: 1.4rem;
}
.cf-depth, .cf-colophon {
  font-family: var(--margin-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--drowned-stone);
  margin-bottom: 0.8rem;
}

/* ==========================================================================
   RESPONSIVE — below 980px the marginalia collapses inline
   ========================================================================== */
@media (max-width: 980px) {
  :root { --gauge-w: 0px; }
  #depth-gauge { display: none; }
  #marine-snow { opacity: 0.4; }
  .chronicle { padding-left: 0; }
  .chapter { padding: 4rem 1.2rem 3rem; }

  .manuscript {
    display: block;
    max-width: 68ch;
    margin: 0 auto;
  }
  .prose { grid-column: auto; }
  .margin-note {
    position: static;
    display: block;
    margin: 1.4rem 0 1.8rem;
    border-left: 2px solid var(--biolum-cyan);
    padding-left: 1rem;
    background: rgba(14,58,95,0.22);
    padding-top: 0.6rem;
    padding-bottom: 0.6rem;
  }
  .margin-note .mn-mark { display: inline; margin-right: 0.4rem; }
  .margin-note .mn-body { display: inline; }
  .hero { padding: 4rem 1.2rem; }
  .code-block { max-width: 100%; }
}

@media (max-width: 560px) {
  body { font-size: 1rem; line-height: 1.7; }
  .hero-title { letter-spacing: 0; }
  .hero-abstract { text-align: left; text-align-last: left; }
  .prose p { text-align: left; }
  .h2-wrap { padding: 1rem 1.2rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .breathing-frame rect { animation: none; }
  .cue-arrow { animation: none; }
}