/* Surface engineering atlas
   ─────────────────────────────────────────────────────────── */

.atlas-hero {
  padding: clamp(3rem, 7vh, 5rem) 0 2rem;
  background: linear-gradient(180deg, var(--paper), var(--chalk));
}

.atlas {
  display: grid;
  grid-template-columns: minmax(12rem, 0.32fr) minmax(0, 0.68fr);
  gap: clamp(1.5rem, 4vw, 3rem);
  align-items: start;
  padding-bottom: clamp(3rem, 7vh, 5rem);
}

@media (max-width: 900px) {
  .atlas { grid-template-columns: 1fr; }
}

.atlas__index {
  position: sticky;
  top: calc(var(--nav-h) + 1rem);
  max-height: calc(100svh - var(--nav-h) - 2rem);
  overflow: auto;
  border-top: 1px solid var(--line);
}

@media (max-width: 900px) {
  .atlas__index {
    position: relative;
    top: auto;
    max-height: none;
    display: flex;
    gap: 0.5rem;
    overflow-x: auto;
    border-top: 0;
    padding-bottom: 0.5rem;
  }
}

.atlas__index a {
  display: grid;
  grid-template-columns: 2rem 1fr;
  gap: 0.55rem;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--line);
  font-size: 0.88rem;
  color: var(--steel);
  transition: color 0.2s;
}

.atlas__index a .mono { color: var(--copper); }

.atlas__index a.is-on,
.atlas__index a:hover { color: var(--ink); }

@media (max-width: 900px) {
  .atlas__index a {
    flex: 0 0 auto;
    border: 1px solid var(--line);
    padding: 0.55rem 0.75rem;
    white-space: nowrap;
    grid-template-columns: auto auto;
  }
  .atlas__index a.is-on {
    border-color: var(--copper);
    background: color-mix(in srgb, var(--copper) 8%, var(--white));
  }
}

.atlas__stage {
  display: grid;
  gap: 1.25rem;
}

.atlas__viz {
  min-height: 14rem;
  border: 1px solid color-mix(in srgb, var(--ink) 12%, transparent);
  background:
    radial-gradient(ellipse 70% 60% at 80% 20%, rgba(184, 115, 51, 0.12), transparent 55%),
    #0e1217;
  display: grid;
  place-items: center;
  padding: 1.25rem;
}

.atlas__viz svg {
  width: min(100%, 34rem);
  height: auto;
}

.atlas__detail {
  border: 1px solid var(--line);
  background: var(--white);
  padding: clamp(1.5rem, 3vw, 2.25rem);
}

.atlas__detail .eyebrow { margin-bottom: 0.65rem; }

.atlas__detail h2 {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 3.2vw, 2.5rem);
  font-weight: 400;
  margin-bottom: 1rem;
}

.atlas__detail p {
  color: var(--ink-soft);
  max-width: 62ch;
  margin-bottom: 1.25rem;
}

.atlas__detail .cta-row { margin-top: 0.5rem; }

.atlas-spine {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.25rem;
}

@media (max-width: 800px) {
  .atlas-spine { grid-template-columns: 1fr; }
}

.atlas-spine article {
  border-top: 1px solid var(--line);
  padding-top: 1rem;
}

.atlas-spine h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 400;
  margin-bottom: 0.4rem;
}

.atlas-spine p { color: var(--steel); font-size: 0.92rem; max-width: 34ch; }