/* ══════════════════════════════════════════════════════════════
   CASE STUDY — editorial reading layout
   Matches index.html visual system
══════════════════════════════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:        #F6F4EE;
  --bg-sunk:   #EFEBE1;
  --paper:     #FAFAF5;
  --ink:       #0E0E0C;
  --ink-80:    #1E1E1B;
  --ink-60:    #4A4944;
  --ink-40:    #7C7A72;
  --ink-20:    #B8B5AB;
  --rule:      #D9D4C5;
  --rule-soft: #E6E1D2;
  --accent:    #C2552B;

  --sans: 'Inter Tight', -apple-system, BlinkMacSystemFont, sans-serif;
  --serif: 'Fraunces', 'Instrument Serif', Georgia, serif;
  --mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, monospace;

  --col-max: 1280px;
  --col-gutter: clamp(24px, 4vw, 64px);
}

body[data-theme="ink"] {
  --bg:        #0E0E0C;
  --bg-sunk:   #17170F;
  --paper:     #151513;
  --ink:       #F3F1E9;
  --ink-80:    #E4E1D6;
  --ink-60:    #A9A59A;
  --ink-40:    #706D63;
  --ink-20:    #3A3832;
  --rule:      #2A2823;
  --rule-soft: #1E1D19;
}

html { font-size: 16px; scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-weight: 400;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  letter-spacing: -0.005em;
  overflow-x: hidden;
}
em { font-family: var(--serif); font-style: italic; font-weight: 400; }
a { color: inherit; text-decoration: none; }

.wrap { max-width: var(--col-max); margin: 0 auto; padding: 0 var(--col-gutter); }
.mono { font-family: var(--mono); }

/* ══════════════════════════════════════════════════════════════
   NAV
══════════════════════════════════════════════════════════════ */
.cs-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in oklab, var(--bg) 90%, transparent);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--rule-soft);
}
.cs-nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.cs-back {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--ink-60);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  transition: color .2s ease;
}
.cs-back:hover { color: var(--ink); }
.cs-back svg { transition: transform .25s ease; }
.cs-back:hover svg { transform: translateX(-3px); }
.cs-nav-brand {
  font-family: var(--sans);
  font-size: 14px;
  font-weight: 500;
  letter-spacing: -0.015em;
  color: var(--ink);
}
.cs-nav-brand em { color: var(--ink-60); font-size: 13px; margin-left: 6px; }

/* ══════════════════════════════════════════════════════════════
   EDITORIAL OPENER
══════════════════════════════════════════════════════════════ */
.cs-opener {
  padding: clamp(56px, 9vh, 120px) 0 0;
}

/* top meta bar: folio on left, year/duration on right */
.cs-top-meta {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 24px;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--ink-60);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  padding-bottom: clamp(32px, 5vh, 56px);
}
.cs-top-meta .folio {
  display: inline-flex;
  align-items: center;
  gap: 12px;
}
.cs-top-meta .folio::before {
  content: '';
  width: 22px; height: 1px;
  background: var(--accent);
  display: inline-block;
}
.cs-top-meta .folio strong { font-weight: 500; color: var(--ink); letter-spacing: 0.14em; }
.cs-top-meta-right { display: flex; gap: 18px; align-items: baseline; }
.cs-top-meta-right .sep { color: var(--ink-20); }

/* MASTHEAD — huge display title */
.cs-masthead {
  font-family: var(--sans);
  font-weight: 500;
  font-size: clamp(56px, 11vw, 168px);
  line-height: 0.92;
  letter-spacing: -0.045em;
  color: var(--ink);
  margin-bottom: clamp(28px, 4vh, 48px);
  max-width: 14ch;
}
.cs-masthead em {
  font-family: var(--serif);
  font-weight: 300;
  font-style: italic;
  letter-spacing: -0.035em;
  color: var(--ink-60);
  display: block;
}

/* THESIS — lede paragraph with drop cap */
.cs-thesis {
  font-family: var(--sans);
  font-size: clamp(20px, 1.9vw, 26px);
  line-height: 1.42;
  color: var(--ink-80);
  max-width: 44ch;
  letter-spacing: -0.015em;
  margin-bottom: clamp(48px, 8vh, 88px);
  position: relative;
}
.cs-thesis em {
  font-family: var(--serif);
  font-style: italic;
  color: var(--ink);
  font-weight: 400;
}
.cs-thesis::first-letter {
  font-family: var(--serif);
  font-style: italic;
  font-weight: 300;
  float: left;
  font-size: clamp(68px, 8.5vw, 108px);
  line-height: 0.82;
  color: var(--accent);
  padding: 4px 12px 0 0;
  letter-spacing: -0.04em;
  text-transform: none;
}

/* FACT STRIP — 4 cells with editorial labels */
.cs-facts {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--rule-soft);
  border-top: 1px solid var(--rule-soft);
  border-bottom: 1px solid var(--rule-soft);
  margin-bottom: clamp(48px, 6vh, 72px);
}
.cs-fact {
  background: var(--bg);
  padding: 22px 0 22px 0;
  padding-right: 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.cs-fact:first-child { padding-left: 0; }
.cs-fact:not(:first-child) { padding-left: 24px; }
.cs-fact .label {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-40);
}
.cs-fact .value {
  font-family: var(--sans);
  font-size: 14.5px;
  font-weight: 500;
  color: var(--ink);
  letter-spacing: -0.005em;
  line-height: 1.3;
}
.cs-fact .value em {
  font-family: var(--serif);
  font-style: italic;
  font-weight: 400;
  color: var(--ink-60);
}

/* FULL-BLEED HERO IMAGE — breaks out of wrap */
.cs-hero-bleed {
  position: relative;
  width: 100vw;
  margin-left: calc(50% - 50vw);
  background: var(--bg-sunk);
  border-top: 1px solid var(--rule-soft);
  border-bottom: 1px solid var(--rule-soft);
  overflow: hidden;
}
.cs-hero-bleed-inner {
  aspect-ratio: 21/9;
  width: 100%;
  position: relative;
}
.cs-hero-bleed img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

/* image caption sitting below the bleed, aligned to the inner column */
.cs-hero-caption {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 24px;
  padding-top: 16px;
  margin-bottom: clamp(56px, 8vh, 96px);
  font-family: var(--mono);
  font-size: 11px;
  color: var(--ink-40);
  letter-spacing: 0.06em;
}
.cs-hero-caption em {
  font-family: var(--serif);
  font-style: italic;
  color: var(--ink-60);
  font-size: 13px;
  letter-spacing: 0;
  text-transform: none;
}

/* ══════════════════════════════════════════════════════════════
   LAYOUT: left rail TOC + reading column
══════════════════════════════════════════════════════════════ */
.cs-shell { padding-bottom: clamp(64px, 10vh, 120px); position: relative; }
.cs-layout {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: clamp(48px, 8vw, 120px);
  align-items: start;
}

.cs-rail {
  position: sticky;
  top: 96px;
  display: flex;
  flex-direction: column;
  gap: 20px;
  padding-top: 8px;
}
.cs-rail-label {
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-40);
  display: flex;
  align-items: center;
  gap: 10px;
}
.cs-rail-label::before {
  content: '';
  width: 18px; height: 1px;
  background: var(--ink-40);
}
.cs-toc { list-style: none; display: flex; flex-direction: column; gap: 2px; }
.cs-toc a {
  display: grid;
  grid-template-columns: 24px 1fr;
  align-items: baseline;
  gap: 10px;
  padding: 8px 10px 8px 14px;
  margin-left: -16px;
  font-family: var(--sans);
  font-size: 13.5px;
  font-weight: 400;
  color: var(--ink-60);
  letter-spacing: -0.005em;
  border-left: 1.5px solid transparent;
  transition: color .2s ease, border-color .2s ease;
}
.cs-toc a:hover { color: var(--ink); }
.cs-toc .num {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--ink-20);
  letter-spacing: 0.08em;
  transition: color .2s ease;
}
.cs-toc a:hover .num { color: var(--ink-60); }
.cs-toc li.active a {
  color: var(--ink);
  border-left-color: var(--accent);
  font-weight: 500;
}
.cs-toc li.active .num { color: var(--accent); }

/* ══════════════════════════════════════════════════════════════
   SECTIONS
══════════════════════════════════════════════════════════════ */
.cs-section {
  padding: 56px 0;
  border-top: 1px solid var(--rule-soft);
}
.cs-section:first-of-type { border-top: none; padding-top: 0; }
.cs-section-head {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 32px;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-60);
}
.cs-section-num { color: var(--ink); font-weight: 500; }
.cs-section-rule {
  height: 1px;
  background: var(--rule-soft);
  width: 40px;
}
.cs-section-tag { color: var(--ink-40); }

.cs-section h2 {
  font-family: var(--sans);
  font-weight: 500;
  font-size: clamp(28px, 3vw, 42px);
  letter-spacing: -0.03em;
  line-height: 1.12;
  color: var(--ink);
  margin-bottom: 28px;
  max-width: 26ch;
}
.cs-section h2 em {
  font-family: var(--serif);
  font-style: italic;
  font-weight: 400;
  letter-spacing: -0.02em;
}
.cs-section p {
  font-family: var(--sans);
  font-size: 16.5px;
  line-height: 1.68;
  color: var(--ink-60);
  max-width: 62ch;
  margin-bottom: 18px;
  letter-spacing: -0.005em;
}
.cs-section p:last-child { margin-bottom: 0; }
.cs-section p em { font-family: var(--serif); font-style: italic; color: var(--ink-80); }
.cs-section p strong { color: var(--ink); font-weight: 500; }
.cs-section p code {
  font-family: var(--mono);
  font-size: 13.5px;
  background: color-mix(in oklab, var(--accent) 8%, transparent);
  color: var(--accent);
  padding: 2px 6px;
  border-radius: 4px;
  letter-spacing: 0;
}

/* ── PULL QUOTE ── */
.cs-pullquote {
  position: relative;
  padding: 36px 0 36px 40px;
  margin: 40px 0;
  border-left: 2px solid var(--accent);
}
.cs-pullquote p {
  font-family: var(--serif);
  font-size: clamp(22px, 2.2vw, 30px);
  line-height: 1.3;
  font-style: italic;
  font-weight: 400;
  color: var(--ink);
  letter-spacing: -0.02em;
  margin: 0;
  max-width: 28ch;
}
.cs-pullquote-cite {
  display: block;
  margin-top: 14px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-40);
  font-style: normal;
}

/* ── FIGURE / SCREEN MOCK ── */
.cs-figure {
  margin: 40px 0;
}
.cs-figure-frame {
  background: var(--bg-sunk);
  border: 1px solid var(--rule-soft);
  border-radius: 10px;
  overflow: hidden;
  position: relative;
  padding: 24px;
}
.cs-figure-frame img { width: 100%; height: auto; display: block; border-radius: 6px; }
.cs-figure-placeholder {
  aspect-ratio: 16/9;
  width: 100%;
  background:
    repeating-linear-gradient(45deg, transparent 0 18px, color-mix(in oklab, var(--ink-20) 30%, transparent) 18px 19px);
  border-radius: 6px;
  display: grid;
  place-items: center;
}
.cs-figure-placeholder .mark {
  background: var(--bg-sunk);
  padding: 10px 16px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border-radius: 100px;
  border: 1px solid var(--rule);
  color: var(--ink-60);
}
.cs-figure-caption {
  margin-top: 16px;
  padding-left: 4px;
  display: flex;
  align-items: baseline;
  gap: 12px;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--ink-40);
  letter-spacing: 0.06em;
}
.cs-figure-caption .label { color: var(--accent); font-weight: 500; }
.cs-figure-caption em { font-family: var(--serif); font-style: italic; color: var(--ink-60); letter-spacing: 0; font-size: 13px; text-transform: none; }

/* ── CHIPS ── */
.cs-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 24px;
}
.cs-chip {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--ink-60);
  letter-spacing: 0.04em;
  padding: 4px 10px;
  border: 1px solid var(--rule);
  border-radius: 100px;
  background: color-mix(in oklab, var(--paper) 50%, transparent);
}

/* ── STATS ── */
.cs-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  margin: 40px 0;
}
.cs-stat {
  padding: 28px 20px 28px 0;
  border-right: 1px solid var(--rule-soft);
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.cs-stat:not(:first-child) { padding-left: 20px; }
.cs-stat:last-child { border-right: none; }
.cs-stat-value {
  font-family: var(--sans);
  font-weight: 500;
  font-size: clamp(32px, 3.4vw, 44px);
  letter-spacing: -0.04em;
  color: var(--ink);
  line-height: 1;
}
.cs-stat-value em { font-family: var(--serif); font-style: italic; font-weight: 300; letter-spacing: -0.03em; color: var(--accent); }
.cs-stat-label {
  font-family: var(--sans);
  font-size: 13px;
  color: var(--ink-60);
  line-height: 1.4;
  letter-spacing: -0.005em;
}

/* ══════════════════════════════════════════════════════════════
   NEXT CASE STUDY
══════════════════════════════════════════════════════════════ */
.cs-next {
  margin-top: 96px;
  padding: 56px 0 8px;
  border-top: 1px solid var(--rule-soft);
}
.cs-next-label {
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-40);
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.cs-next-label::before { content: ''; width: 22px; height: 1px; background: var(--accent); }
.cs-next-link {
  display: flex;
  align-items: baseline;
  gap: 22px;
  color: var(--ink);
  transition: color .3s ease;
}
.cs-next-link:hover { color: var(--accent); }
.cs-next-title {
  font-family: var(--sans);
  font-weight: 500;
  font-size: clamp(36px, 4.5vw, 64px);
  letter-spacing: -0.035em;
  line-height: 1;
}
.cs-next-title em { font-family: var(--serif); font-style: italic; font-weight: 300; color: var(--ink-60); }
.cs-next-link:hover .cs-next-title em { color: var(--accent); }
.cs-next-arrow {
  display: inline-flex;
  transition: transform .35s cubic-bezier(0.22, 1, 0.36, 1);
}
.cs-next-link:hover .cs-next-arrow { transform: translateX(8px); }
.cs-next-kicker {
  font-family: var(--sans);
  font-size: 15px;
  color: var(--ink-60);
  margin-top: 14px;
  max-width: 44ch;
  line-height: 1.55;
}

/* ══════════════════════════════════════════════════════════════
   FOOTER
══════════════════════════════════════════════════════════════ */
.cs-footer {
  border-top: 1px solid var(--rule-soft);
  padding: 32px 0 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-top: 80px;
}
.cs-footer-copy {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--ink-40);
  letter-spacing: 0.06em;
}

/* ══════════════════════════════════════════════════════════════
   RESPONSIVE
══════════════════════════════════════════════════════════════ */
@media (max-width: 900px) {
  .cs-layout { grid-template-columns: 1fr; gap: 32px; }
  .cs-rail {
    position: static;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 6px 8px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--rule-soft);
  }
  .cs-rail-label { width: 100%; }
  .cs-toc { flex-direction: row; flex-wrap: wrap; gap: 2px; }
  .cs-toc a {
    padding: 6px 10px;
    margin-left: 0;
    border-left: none;
    border-bottom: 1.5px solid transparent;
    grid-template-columns: auto auto;
    gap: 6px;
  }
  .cs-toc li.active a { border-left: none; border-bottom-color: var(--accent); }
  .cs-facts { grid-template-columns: repeat(2, 1fr); }
  .cs-fact:nth-child(2) { padding-right: 0; }
  .cs-fact:nth-child(3) { padding-left: 0; }
  .cs-stats { grid-template-columns: 1fr; }
  .cs-stat { border-right: none; border-bottom: 1px solid var(--rule-soft); padding-right: 0; }
  .cs-stat:not(:first-child) { padding-left: 0; }
  .cs-stat:last-child { border-bottom: none; }
  .cs-thesis::first-letter { font-size: 68px; padding-right: 10px; }
}
@media (max-width: 600px) {
  .cs-top-meta { flex-direction: column; align-items: flex-start; gap: 12px; }
  .cs-facts { grid-template-columns: 1fr; }
  .cs-fact { padding: 18px 0 !important; border-bottom: 1px solid var(--rule-soft); }
  .cs-fact:last-child { border-bottom: none; }
  .cs-hero-bleed-inner { aspect-ratio: 4/3; }
  .cs-hero-caption { flex-direction: column; gap: 6px; }
}