:root {
  --carbon: #070707;
  --rice: #F4F0E8;
  --graphite: #2A2926;
  --ash: #C9C1B5;
  --vermilion: #E23223;
  --plum: #3A1118;
  --serif: "Noto Serif JP", "Hiragino Mincho ProN", "Yu Mincho", Georgia, serif;
  --sans: "Instrument Sans", Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", "SFMono-Regular", Consolas, monospace;
}

/* Design language anchors: use IBM Plex Mono sparingly for timestamps; Interruption** Interruptio — the layout breaks into cropped strips resembling station signs. */

* { box-sizing: border-box; }

html {
  background: var(--rice);
  color: var(--graphite);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  overflow-x: hidden;
  font-family: var(--sans);
  background: var(--rice);
}

button { font: inherit; }

.grain {
  position: fixed;
  inset: 0;
  z-index: 20;
  pointer-events: none;
  opacity: .42;
  mix-blend-mode: multiply;
  background:
    radial-gradient(circle at 20% 30%, rgba(7, 7, 7, .08) 0 1px, transparent 1px 7px),
    radial-gradient(circle at 72% 61%, rgba(58, 17, 24, .06) 0 1px, transparent 1px 9px),
    linear-gradient(90deg, rgba(7, 7, 7, .025) 1px, transparent 1px),
    linear-gradient(0deg, rgba(7, 7, 7, .018) 1px, transparent 1px);
  background-size: 17px 19px, 23px 29px, 5px 100%, 100% 7px;
}

.mono { font-family: var(--mono); letter-spacing: .09em; text-transform: uppercase; }

.fixed-labels {
  position: fixed;
  z-index: 30;
  inset: 24px 28px auto 28px;
  display: flex;
  justify-content: space-between;
  color: var(--graphite);
  font-size: 10px;
  pointer-events: none;
  mix-blend-mode: difference;
}

.fixed-labels span { color: var(--ash); }

.thread-layer {
  position: fixed;
  inset: 0;
  z-index: 16;
  pointer-events: none;
}

.red-thread {
  position: absolute;
  left: 0;
  top: var(--thread-y, 78vh);
  width: var(--thread-width, 2px);
  height: 2px;
  background: var(--vermilion);
  box-shadow: 0 0 0 1px rgba(226, 50, 35, .12), 0 0 18px rgba(226, 50, 35, .18);
  transform-origin: left center;
  transition: top .55s cubic-bezier(.76, 0, .24, 1), height .35s linear;
}

.thread-knot {
  position: absolute;
  left: var(--knot-x, 73vw);
  top: calc(var(--thread-y, 78vh) - 7px);
  width: 16px;
  height: 16px;
  border: 2px solid var(--vermilion);
  border-radius: 50%;
  background: var(--rice);
  opacity: var(--knot-opacity, 0);
  transform: scale(var(--knot-scale, .5));
  transition: opacity .3s ease, transform .3s ease, top .55s cubic-bezier(.76, 0, .24, 1);
}

.chapter {
  min-height: 100vh;
  position: relative;
  overflow: hidden;
  display: grid;
  padding: 7vw;
  border-bottom: 1px solid rgba(42, 41, 38, .22);
}

.chapter::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(90deg, transparent 0 48%, rgba(201, 193, 181, .22) 48% 48.2%, transparent 48.2%);
}

.chapter-unsent {
  min-height: 100svh;
  padding: 0;
  background: var(--rice);
}

.case-mark {
  position: absolute;
  left: clamp(28px, 7vw, 104px);
  bottom: clamp(38px, 9vw, 118px);
}

.receipt, .tag {
  margin: 0 0 18px;
  font-size: 10px;
  color: var(--graphite);
}

h1, h2 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 500;
  color: var(--carbon);
  letter-spacing: .12em;
}

h1 {
  font-size: clamp(44px, 9vw, 136px);
  line-height: .84;
}

h1 span { color: var(--ash); }
h1 em { font-style: normal; position: relative; }

.message-door {
  position: absolute;
  right: 0;
  top: 0;
  width: clamp(250px, 34vw, 560px);
  height: 100%;
  background: var(--carbon);
  transform: translateX(var(--door-shift, 0));
  transition: transform .75s cubic-bezier(.76, 0, .24, 1);
  box-shadow: -18px 0 0 rgba(42, 41, 38, .05), -40px 0 70px rgba(7, 7, 7, .18);
}

.door-cut {
  position: absolute;
  left: 12%;
  right: 18%;
  height: 1px;
  background: rgba(244, 240, 232, .22);
}
.door-cut.one { top: 18%; }
.door-cut.two { top: 51%; right: 38%; }
.door-cut.three { bottom: 17%; left: 42%; }

.story-cue {
  position: absolute;
  right: clamp(28px, 38vw, 580px);
  bottom: clamp(30px, 8vw, 96px);
  border: 1px solid var(--graphite);
  background: transparent;
  color: var(--graphite);
  padding: 15px 20px;
  font-size: 12px;
  letter-spacing: .18em;
  text-transform: lowercase;
  cursor: pointer;
}

.story-cue::after {
  content: "";
  display: inline-block;
  width: 9px;
  height: 9px;
  margin-left: 18px;
  background: var(--vermilion);
  border-radius: 50%;
  animation: dotPulse 3.8s steps(1) infinite;
}

.cursor-mark {
  position: absolute;
  left: clamp(32px, 7vw, 110px);
  bottom: clamp(26px, 5vw, 66px);
  width: 2px;
  height: 24px;
  background: var(--vermilion);
  animation: cursorBlink 4s steps(1) infinite;
}

.chapter-approach {
  grid-template-columns: minmax(210px, .9fr) 18vw minmax(210px, 1fr);
  align-items: center;
  gap: 3vw;
}

.paper-column {
  min-height: 58vh;
  border: 1px solid rgba(42, 41, 38, .42);
  background: rgba(244, 240, 232, .76);
  padding: clamp(28px, 5vw, 70px);
  box-shadow: 16px 18px 0 rgba(201, 193, 181, .35);
  transform: translateX(var(--column-shift, 0));
  transition: transform .2s linear;
}

.receiver { margin-top: 16vh; box-shadow: -16px 18px 0 rgba(201, 193, 181, .35); }
.sender { margin-bottom: 15vh; }

h2 { font-size: clamp(38px, 6vw, 92px); line-height: .96; }
.paper-column p:not(.tag), .quiet-line, .folded-note p:last-child {
  font-size: clamp(17px, 1.6vw, 24px);
  line-height: 1.5;
  max-width: 520px;
}

.gap-field {
  min-height: 70vh;
  position: relative;
  border-left: 1px dashed var(--ash);
  border-right: 1px dashed var(--ash);
}

.gap-field span {
  position: absolute;
  font-family: var(--mono);
  color: var(--vermilion);
  opacity: .78;
  font-size: 13px;
}
.gap-field span:nth-child(1) { left: 38%; top: 11%; }
.gap-field span:nth-child(2) { left: 61%; top: 27%; }
.gap-field span:nth-child(3) { left: 46%; top: 45%; }
.gap-field span:nth-child(4) { left: 54%; top: 60%; }
.gap-field span:nth-child(5) { left: 33%; top: 73%; }
.gap-field span:nth-child(6) { left: 58%; top: 84%; }
.gap-field span:nth-child(7) { left: 45%; top: 91%; }

.chapter-interruption {
  background: var(--graphite);
  color: var(--rice);
  padding-top: 14vh;
  align-content: center;
}

.strip-board { display: grid; gap: clamp(12px, 2vw, 28px); width: min(980px, 84vw); }

.strip {
  min-height: 72px;
  display: grid;
  grid-template-columns: 170px 1fr;
  align-items: center;
  padding: 0 28px;
  overflow: hidden;
  clip-path: inset(0 var(--strip-cut, 0) 0 0);
  transition: clip-path .25s linear, transform .25s linear;
}

.strip span { font-family: var(--mono); font-size: 11px; color: var(--ash); }
.strip strong { font-family: var(--serif); font-weight: 500; letter-spacing: .1em; font-size: clamp(22px, 4vw, 58px); white-space: nowrap; }
.strip.black { background: var(--carbon); }
.strip.receipt { background: var(--rice); color: var(--graphite); border-left: 10px dotted var(--ash); }
.strip.film { background: var(--ash); color: var(--carbon); transform: translateX(8vw); }
.strip.short { width: 74%; transform: translateX(18vw); }

.censor-scene {
  position: absolute;
  right: 6vw;
  bottom: 8vh;
  width: min(620px, 78vw);
  font-family: var(--serif);
  font-size: clamp(30px, 5vw, 76px);
  line-height: 1.05;
  letter-spacing: .09em;
}

.censor-scene p { margin: 8px 0; }
.censor-scene span {
  position: relative;
  display: inline-block;
  color: rgba(244, 240, 232, var(--reveal, .12));
  transition: color .2s linear;
}
.censor-scene span::after {
  content: "";
  position: absolute;
  inset: .14em -.05em .16em -.05em;
  background: var(--carbon);
  transform: scaleX(var(--bar, 1));
  transform-origin: right center;
  transition: transform .2s linear;
}

.chapter-reply { background: var(--rice); align-items: center; }
.reply-stage { width: min(1100px, 88vw); margin-left: auto; margin-right: auto; }
.reply-stage h2 { max-width: 850px; }
.route-names {
  margin: 13vh 0 8vh;
  display: flex;
  justify-content: space-between;
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: .16em;
}
.route-names span { border-top: 1px solid var(--graphite); padding-top: 16px; min-width: 150px; }
.black-knot {
  width: min(420px, 58vw);
  height: 120px;
  margin-left: auto;
  background: var(--carbon);
  position: relative;
  box-shadow: 0 16px 0 var(--plum);
}
.black-knot span {
  position: absolute;
  left: 50%; top: 50%;
  width: 34px; height: 34px;
  border: 2px solid var(--vermilion);
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

.chapter-afterimage {
  min-height: 100svh;
  background: var(--rice);
  align-items: center;
}

.after-grid {
  display: grid;
  grid-template-columns: 1fr 1.3fr;
  gap: 8vw;
  align-items: end;
  width: 100%;
}
.folded-note {
  position: relative;
  border: 1px solid var(--ash);
  padding: clamp(28px, 5vw, 64px);
  min-height: 280px;
  background:
    linear-gradient(135deg, transparent 0 38px, rgba(201, 193, 181, .42) 39px 40px, transparent 41px),
    repeating-linear-gradient(45deg, rgba(7,7,7,.025) 0 2px, transparent 2px 9px);
}
.folded-note::after {
  content: "";
  position: absolute;
  top: 0; right: 0;
  border-top: 54px solid var(--ash);
  border-left: 54px solid transparent;
}
.final-domain {
  justify-self: end;
  font-family: var(--serif);
  font-size: clamp(64px, 15vw, 230px);
  line-height: .78;
  letter-spacing: .16em;
  color: var(--carbon);
  transform: translateX(var(--final-shift, 0));
}
.final-domain .ghost {
  color: rgba(42, 41, 38, var(--ghost-opacity, .18));
  transition: opacity .3s linear;
}
.final-domain strong { font-weight: 500; }
.final-underline {
  grid-column: 2;
  justify-self: end;
  width: clamp(80px, 15vw, 240px);
  height: 3px;
  background: var(--vermilion);
  margin-right: 1.1em;
}

@keyframes cursorBlink {
  0%, 6% { opacity: 1; }
  7%, 100% { opacity: 0; }
}

@keyframes dotPulse {
  0%, 8% { transform: scale(1); opacity: 1; }
  9%, 100% { transform: scale(.35); opacity: .35; }
}

@media (max-width: 820px) {
  .fixed-labels { inset: 16px 18px auto 18px; }
  .label-left { display: none; }
  .message-door { width: 32vw; min-width: 116px; }
  .story-cue { right: 24px; bottom: 38vh; background: var(--rice); }
  .chapter { padding: 22vw 7vw 14vw; }
  .chapter-approach { grid-template-columns: 1fr; gap: 10vh; }
  .paper-column, .receiver, .sender { margin: 0; min-height: auto; }
  .gap-field { min-height: 26vh; }
  .strip { grid-template-columns: 1fr; gap: 8px; padding: 18px; }
  .strip.film, .strip.short { transform: none; width: 100%; }
  .censor-scene { position: relative; right: auto; bottom: auto; margin-top: 12vh; }
  .after-grid { grid-template-columns: 1fr; }
  .final-underline { grid-column: 1; }
}