/* =====================================================================
   case.css — case study template: sticky contents rail + scrolling body
   ===================================================================== */

/* ---------- Head ---------- */
.case-head {
  padding-block: clamp(1.5rem, 3vw, 2.5rem) clamp(2rem, 4vw, 3rem);
  border-bottom: 1px solid var(--line);
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: var(--fs-small);
  color: var(--fg-muted);
  margin-bottom: clamp(1.5rem, 3.5vw, 2.5rem);
  transition: color 0.15s ease;
}

.back-link:hover { color: var(--fg); }
.back-link span { transition: transform 0.18s ease; }
.back-link:hover span { transform: translateX(-3px); }

.case-head .label { display: block; margin-bottom: 0.9rem; }

.case-title {
  font-family: var(--font-display);
  font-size: clamp(1.875rem, 4.2vw, 3.25rem);
  font-weight: var(--display-weight);
  letter-spacing: var(--display-tracking);
  line-height: 1.04;
  text-wrap: balance;
  max-width: 19ch;
}

.case-lede {
  margin-top: clamp(1.25rem, 2.5vw, 1.75rem);
  color: var(--fg-muted);
  max-width: 58ch;
}

/* ---------- Two-column body ---------- */
.case-layout {
  display: grid;
  grid-template-columns: 13rem minmax(0, 1fr);
  gap: clamp(2rem, 5vw, 4.25rem);
  padding-block: clamp(2rem, 4vw, 3rem);
}

/* ---------- Contents rail (sticky) ---------- */
.case-rail {
  position: sticky;
  top: var(--space-md);
  align-self: start;
  max-height: calc(100vh - var(--space-md) * 2);
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
}

.case-rail__title { display: block; margin-bottom: 1rem; }

.case-toc { margin-bottom: var(--space-md); }

.case-toc__link {
  display: grid;
  grid-template-columns: 1.6rem minmax(0, 1fr);
  gap: 0.35rem;
  padding-block: 0.34rem;
  font-size: var(--fs-small);
  color: var(--fg-muted);
  transition: color 0.15s ease;
}

.case-toc__link:hover { color: var(--fg); }

.case-toc__num {
  font-size: var(--fs-label);
  letter-spacing: 0.08em;
  color: var(--fg-faint);
  padding-top: 0.15em;
  font-variant-numeric: tabular-nums;
}

.case-toc__link.is-active {
  color: var(--fg);
  font-weight: 500;
}

.case-toc__link.is-active .case-toc__num { color: var(--fg); }

/* ---------- Rail meta ---------- */
.case-meta { display: grid; gap: 1.15rem; padding-top: var(--space-sm); }

.case-meta__label { display: block; margin-bottom: 0.3rem; }

.case-meta__value {
  font-size: var(--fs-small);
  line-height: 1.45;
}

/* ---------- Sections ---------- */
.case-section { padding-block: clamp(1.75rem, 3.5vw, 2.75rem); }
.case-section + .case-section { border-top: 1px solid var(--line); }

.case-section__head {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  font-family: var(--font-display);
  font-size: clamp(1.125rem, 1.7vw, 1.4rem);
  font-weight: var(--weight-strong);
  letter-spacing: -0.02em;
  margin-bottom: 1.1rem;
}

.case-section__num {
  flex: none;
  font-family: var(--font-body);
  font-size: var(--fs-label);
  font-weight: 500;
  letter-spacing: 0.13em;
  color: var(--fg-faint);
  font-variant-numeric: tabular-nums;
}

.case-section p {
  max-width: 68ch;
  color: var(--fg-muted);
}

.case-section p + p { margin-top: 0.9rem; }

.case-section .stats { margin-top: clamp(1.5rem, 3vw, 2rem); }

/* Scroll-spy targets clear the top of the viewport when jumped to */
.case-section,
.case-hero { scroll-margin-top: var(--space-md); }

/* ---------- Figures ---------- */
.case-hero { margin-bottom: clamp(0.5rem, 1.5vw, 1rem); }

.figure { margin-top: clamp(1.5rem, 3vw, 2rem); }

/* Captions run the width of the figure they label, not the prose measure. */
.figure figcaption {
  margin-top: 0.7rem;
  font-size: var(--fs-small);
  color: var(--fg-faint);
}

/* ---------- Next case study ---------- */
.next-case {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: end;
  gap: var(--space-sm);
  padding-top: var(--space-md);
  border-top: 1px solid var(--rule);
}

.next-case .label { display: block; margin-bottom: 0.9rem; }

.next-case__title {
  display: block;   /* it is a <span>; max-width needs a block box */
  font-family: var(--font-display);
  font-size: clamp(1.375rem, 2.8vw, 2rem);
  font-weight: var(--weight-strong);
  letter-spacing: -0.025em;
  line-height: 1.12;
  text-wrap: balance;
  max-width: 20ch;
}

.next-case:hover .work-item__arrow { transform: translateX(3px); }
.next-case:hover .next-case__title {
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 1px;
}

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
  .case-layout {
    grid-template-columns: 1fr;
    gap: var(--space-md);
  }

  /* The rail stops being a rail — it becomes a summary above the body. */
  .case-rail {
    position: static;
    max-height: none;
    overflow: visible;
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid var(--line);
  }

  .case-toc {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: var(--space-sm);
    margin-bottom: var(--space-sm);
  }

  .case-meta { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: var(--space-sm); }
}

@media (max-width: 540px) {
  .case-toc { grid-template-columns: 1fr; }
  .case-meta { grid-template-columns: 1fr; }
}