/* ==========================================================================
   layout.css — page shell, section chrome, fixed UI (topbar / rail / menu)
   ========================================================================== */

/* --------------------------------------------------------------------------
   Shell & sections
   -------------------------------------------------------------------------- */

.shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  position: relative;
  isolation: isolate;
  background: var(--section-bg);
  color: var(--section-fg);
  padding-block: var(--section-pad);
  overflow: clip;
}

.section--full {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  align-content: center;
  min-height: 100svh;
  padding-block: clamp(6rem, 12vh, 10rem);
}

.section--flush {
  padding-block: 0;
}

.section--tight {
  padding-block: clamp(3rem, 6vh, 5rem);
}

/* hairline that draws itself between chapters */
.section::after {
  content: "";
  position: absolute;
  inset-inline: var(--gutter);
  top: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line-strong) 18%, var(--line-strong) 82%, transparent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 1.4s var(--ease-out);
}

.section.is-entered::after {
  transform: scaleX(1);
}

.section--no-rule::after {
  display: none;
}

/* faint outline chapter numeral in the corner of each section */
.section__watermark {
  position: absolute;
  z-index: -1;
  right: calc(var(--gutter) - 0.1em);
  bottom: -0.18em;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(9rem, 26vw, 26rem);
  line-height: 0.7;
  letter-spacing: -0.06em;
  color: transparent;
  -webkit-text-stroke: 1px var(--line);
  opacity: 0.55;
  pointer-events: none;
  user-select: none;
}

/* --------------------------------------------------------------------------
   Section heads & split layouts
   -------------------------------------------------------------------------- */

.section-head {
  display: flex;
  flex-direction: column;
  gap: clamp(1rem, 2.2vw, 1.75rem);
  max-width: 44rem;
}

.section-heading {
  max-width: 16ch;
}

.section-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.5rem;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.45em;
  padding: 0.42em 0.9em;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-pill);
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--text-muted);
  white-space: nowrap;
}

.tag::before {
  content: "";
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--orange);
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
  gap: clamp(2.25rem, 6vw, 6rem);
  align-items: center;
}

.split--reverse {
  grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
}

.split--reverse .split__copy {
  order: 2;
}

.split--reverse .split__media {
  order: 1;
}

.split__copy {
  display: flex;
  flex-direction: column;
  gap: clamp(1.1rem, 2.4vw, 1.9rem);
  max-width: 34rem;
}

.split__media {
  min-width: 0;
}

/* full-bleed photographic chapters */
.plate {
  position: relative;
  min-height: 100svh;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  align-items: end;
  overflow: clip;
}

.plate__media {
  position: absolute;
  inset: 0;
  z-index: -2;
}

.plate__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.plate__scrim {
  position: absolute;
  inset: 0;
  z-index: -1;
  background:
    linear-gradient(180deg, rgb(10 10 12 / 0.55) 0%, transparent 30%, transparent 46%, rgb(10 10 12 / 0.92) 100%),
    linear-gradient(96deg, rgb(10 10 12 / 0.92) 0%, rgb(10 10 12 / 0.62) 34%, rgb(10 10 12 / 0) 66%);
}

.plate__body {
  width: 100%;
  padding-block: clamp(3rem, 8vh, 6rem);
  color: var(--on-dark-strong);
}

/* --------------------------------------------------------------------------
   Top bar
   -------------------------------------------------------------------------- */

.topbar {
  position: fixed;
  inset-inline: 0;
  top: 0;
  z-index: var(--z-topbar);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: clamp(1rem, 2.4vh, 1.6rem) var(--gutter);
  color: #fff;
  transition: color var(--dur-2) var(--ease-out);
  pointer-events: none;
}

/* The bar switches ink/paper based on the section passing underneath it. */
html[data-tone="light"] .topbar,
html[data-tone="accent"] .topbar {
  color: var(--ink);
}

.topbar > * {
  pointer-events: auto;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  font-family: var(--font-display);
  font-size: var(--step-0);
  font-weight: 600;
  letter-spacing: -0.01em;
}

.brand__mark {
  display: grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  border: 1px solid currentColor;
  border-radius: 50%;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.brand__slash {
  opacity: 0.45;
}

.brand__project {
  opacity: 0.7;
  font-weight: 400;
}

.topbar__meta {
  display: flex;
  align-items: center;
  gap: clamp(0.85rem, 2vw, 1.75rem);
  font-family: var(--font-display);
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.topbar__counter {
  display: inline-flex;
  gap: 0.4rem;
  align-items: baseline;
  font-variant-numeric: tabular-nums;
  opacity: 0.85;
}

.topbar__counter b {
  font-weight: 700;
}

.topbar__counter span {
  opacity: 0.5;
}

.menu-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.55rem 0.9rem 0.55rem 1rem;
  border: 1px solid currentColor;
  border-radius: var(--radius-pill);
  font-family: var(--font-display);
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transition: background var(--dur-1), color var(--dur-1);
}

.menu-toggle:hover {
  background: #fff;
  color: #000;
}

.menu-toggle__icon {
  display: grid;
  gap: 3px;
  width: 14px;
}

.menu-toggle__icon i {
  display: block;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--dur-1) var(--ease-out), opacity var(--dur-1);
}

.menu-toggle[aria-expanded="true"] .menu-toggle__icon i:nth-child(1) {
  transform: translateY(4.5px) rotate(45deg);
}

.menu-toggle[aria-expanded="true"] .menu-toggle__icon i:nth-child(2) {
  opacity: 0;
}

.menu-toggle[aria-expanded="true"] .menu-toggle__icon i:nth-child(3) {
  transform: translateY(-4.5px) rotate(-45deg);
}

/* --------------------------------------------------------------------------
   Chapter rail (desktop): a quiet map of the page
   -------------------------------------------------------------------------- */

.rail {
  position: fixed;
  right: clamp(1rem, 2.2vw, 2rem);
  top: 50%;
  z-index: var(--z-rail);
  transform: translateY(-50%);
  color: #fff;
  transition: color var(--dur-2) var(--ease-out);
}

html[data-rail-tone="light"] .rail {
  color: var(--ink);
}

.rail__list {
  display: grid;
  gap: 0.55rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.rail__link {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 0.6rem;
  color: currentColor;
  font-family: var(--font-display);
  font-size: 0.62rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.rail__label {
  opacity: 0;
  transform: translateX(6px);
  transition: opacity var(--dur-1), transform var(--dur-1) var(--ease-out);
  white-space: nowrap;
}

.rail__tick {
  width: 14px;
  height: 2px;
  background: currentColor;
  opacity: 0.35;
  border-radius: 2px;
  transition: width var(--dur-1) var(--ease-out), opacity var(--dur-1);
}

.rail__link:hover .rail__label,
.rail__link:focus-visible .rail__label,
.rail__link.is-active .rail__label {
  opacity: 0.9;
  transform: none;
}

.rail__link:hover .rail__tick,
.rail__link.is-active .rail__tick {
  width: 26px;
  opacity: 1;
}

.rail__link.is-active .rail__tick {
  background: currentColor;
}

@media (max-width: 1180px), (hover: none) {
  .rail {
    display: none;
  }
}

/* --------------------------------------------------------------------------
   Full-screen index / menu
   -------------------------------------------------------------------------- */

.nav {
  position: fixed;
  inset: 0;
  z-index: var(--z-nav);
  display: grid;
  grid-template-rows: auto 1fr auto;
  background:
    linear-gradient(180deg, rgb(8 8 10 / 0.42), transparent 24%, transparent 76%, rgb(8 8 10 / 0.42)),
    var(--scrim);
  backdrop-filter: blur(28px) saturate(1.08);
  color: var(--on-dark-strong);
  padding: clamp(1.25rem, 3vh, 2rem) var(--gutter) clamp(1.5rem, 4vh, 2.5rem);
  visibility: hidden;
  opacity: 0;
  clip-path: inset(0 0 100% 0);
  transition: clip-path 0.75s var(--ease-out), opacity 0.4s linear, visibility 0.75s;
}

.nav[data-open="true"] {
  visibility: visible;
  opacity: 1;
  clip-path: inset(0 0 0 0);
}

.nav__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid rgb(247 243 234 / 0.22);
}

.nav__head p {
  font-family: var(--font-display);
  font-size: var(--step--1);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: rgb(247 243 234 / 0.8);
}

.nav__close {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.5rem 0.95rem;
  border: 1px solid rgb(247 243 234 / 0.3);
  border-radius: var(--radius-pill);
  font-size: var(--step--1);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transition: border-color var(--dur-1), color var(--dur-1);
}

.nav__close:hover {
  border-color: var(--orange);
  color: var(--orange-bright);
}

.nav__list {
  align-self: center;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.15rem 3rem;
  margin: 0;
  padding: clamp(1.5rem, 4vh, 3rem) 0;
  list-style: none;
  counter-reset: chapter;
}

.nav__item {
  counter-increment: chapter;
}

.nav__link {
  display: grid;
  grid-template-columns: 2.6rem 1fr auto;
  align-items: baseline;
  gap: 1rem;
  padding: clamp(0.45rem, 1.2vh, 0.8rem) 0;
  border-bottom: 1px solid rgb(247 243 234 / 0.16);
  font-family: var(--font-display);
  font-size: clamp(1.2rem, 2.1vw, 2rem);
  font-weight: 500;
  letter-spacing: -0.02em;
  transition: color var(--dur-1), padding-left var(--dur-2) var(--ease-out);
}

.nav__link::before {
  content: counter(chapter, decimal-leading-zero);
  font-family: var(--font-body);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  color: rgb(247 243 234 / 0.7);
}

.nav__link::after {
  content: "↗";
  font-size: 0.8em;
  opacity: 0.3;
  transform: translateX(-6px);
  transition: transform var(--dur-1) var(--ease-out), opacity var(--dur-1);
}

.nav__link:hover,
.nav__link:focus-visible {
  color: var(--orange-bright);
  padding-left: 0.6rem;
}

.nav__link:hover::after,
.nav__link:focus-visible::after {
  opacity: 1;
  transform: none;
}

.nav__link[aria-current="true"] {
  color: var(--orange);
}

.nav__foot {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-top: 1.25rem;
  border-top: 1px solid rgb(247 243 234 / 0.22);
  font-size: var(--step--1);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: rgb(247 243 234 / 0.8);
}

.nav__foot a {
  color: var(--on-dark-muted);
  border-bottom: 1px solid transparent;
  transition: color var(--dur-1), border-color var(--dur-1);
}

.nav__foot a:hover {
  color: var(--orange-bright);
  border-color: currentColor;
}

body.has-nav-open {
  overflow: hidden;
}

/* --------------------------------------------------------------------------
   Small screens
   -------------------------------------------------------------------------- */

@media (max-width: 900px) {
  .split,
  .split--reverse {
    grid-template-columns: minmax(0, 1fr);
    gap: clamp(1.75rem, 5vw, 2.5rem);
  }

  /* On narrow screens every chapter reads copy-first; the reversed chapters
     only change sides on desktop. */
  .split--reverse .split__copy {
    order: 1;
  }

  .split--reverse .split__media {
    order: 2;
  }

  .split__copy {
    max-width: none;
  }

  .nav__list {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
    padding-block: 1rem;
    overflow-y: auto;
  }

  .nav__link {
    font-size: clamp(1.1rem, 4.4vw, 1.5rem);
    grid-template-columns: 2rem 1fr auto;
  }

  .section__watermark {
    opacity: 0.38;
  }
}

@media (max-width: 640px) {
  .topbar__meta .topbar__counter {
    display: none;
  }

  .brand__project,
  .brand__slash {
    display: none;
  }

  .topbar {
    padding-inline: 1.1rem;
  }
}