/* ============================================================
   layout.css — grid, chapter scaffolding, canvas stage
   ============================================================ */

/* Ambient Three.js canvas sits behind everything */
.stage-canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
  opacity: 0;
  transition: opacity 1.6s var(--ease);
}
body.is-ready .stage-canvas { opacity: 1; }

main { position: relative; z-index: 1; }

/* The gateway is the product experience. Chapter sections remain in the DOM
  as the single source for overlay content, but never become a scroll page. */
body.immersive-mode main > :not(.icon-scene),
body.immersive-mode .meniscus,
body.immersive-mode .gauge,
body.immersive-mode .nav { display: none; }

/* ---------- 12 column grid ---------- */
.grid {
  width: 100%;
  max-width: 1680px;
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  column-gap: clamp(1rem, 2vw, 2.4rem);
  row-gap: var(--flow);
  align-content: center;
}

/* ---------- chapter shell ---------- */
.chapter {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: center;
  padding-block: clamp(7rem, 14vh, 12rem);
  border-top: 1px solid var(--rule);
}
.chapter--hero { border-top: 0; }

/* Chapter numeral — set in the display serif, not a mono badge */
.chapter__num {
  grid-column: 1 / 2;
  grid-row: 1;
  align-self: start;
  font-size: var(--t-lg);
  line-height: 1;
  color: var(--accent);
  opacity: 0.55;
}

.chapter__head {
  grid-column: 2 / 8;
  grid-row: 1;
  display: flex;
  flex-direction: column;
  gap: var(--flow);
}

.chapter__aside {
  grid-column: 9 / 13;
  grid-row: 1;
  align-self: end;
  display: flex;
  flex-direction: column;
  gap: calc(var(--flow) * 0.9);
}

/* Reserved placeholders for future Three.js scenes */
.chapter__stage {
  grid-column: 2 / 13;
  grid-row: 2;
  min-height: clamp(8rem, 22vh, 16rem);
  border: 1px dashed var(--rule);
  border-radius: 2px;
  opacity: 0.45;
}

/* when a chapter already fills row 2, the scene mount drops to row 3 */
.rooms ~ .chapter__stage,
.scaleline ~ .chapter__stage,
.lab ~ .chapter__stage,
.readouts ~ .chapter__stage { grid-row: 3; }

.chapter--wide .chapter__head { grid-column: 2 / 10; }
.chapter--finale { min-height: 120svh; }

/* ---------- footer ---------- */
.footer {
  position: relative;
  z-index: 1;
  border-top: 1px solid var(--rule);
  padding-block: clamp(4rem, 12vh, 9rem) clamp(2rem, 5vh, 4rem);
  background: color-mix(in srgb, var(--bg-raised) 70%, transparent);
  backdrop-filter: blur(14px);
}
.footer .grid { row-gap: clamp(2.5rem, 6vh, 5rem); }

.footer__lead { grid-column: 1 / 7; }
.footer__contact { margin-top: 2rem; max-width: 34rem; }
.footer__contact h3 { margin-bottom: 1rem; }
.footer__contact form { display: grid; gap: 0.55rem; }
.footer__contact [data-contact-status] { margin: 0; color: var(--ink-soft); font-size: var(--t-sm); line-height: 1.55; }
.footer__contact [data-contact-status]:empty { display: none; }
.footer__contact [data-contact-status].ov-form__status--success { color: var(--accent); }
.footer__contact [data-contact-status].ov-form__status--error { color: #b3261e; }
.footer__contact label { color: var(--ink-soft); font-size: var(--t-sm); }
.footer__contact input,
.footer__contact textarea {
  width: 100%;
  padding: 0.7rem 0.8rem;
  border: 1px solid var(--glass-edge);
  border-radius: 3px;
  background: var(--glass-bg);
  color: var(--ink);
  font: inherit;
}
.footer__contact textarea { min-height: 7rem; resize: vertical; }
.footer__contact input:focus-visible,
.footer__contact textarea:focus-visible { outline: 1px solid var(--accent); outline-offset: 2px; }
.footer__contact button {
  justify-self: start;
  margin-top: 0.5rem;
  padding: 0.65rem 1rem;
  border: 1px solid var(--accent);
  border-radius: 3px;
  color: var(--ink);
  transition: background var(--fast) var(--ease), color var(--fast) var(--ease);
}
.footer__contact button:hover,
.footer__contact button:focus-visible { background: var(--accent); color: var(--abyss); }
.footer__nav {
  grid-column: 9 / 13;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}
.footer__legal {
  grid-column: 1 / 13;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-size: var(--t-xs);
  color: var(--ink-soft);
}

/* Fallback when WebGL is unavailable — the page keeps its depth without
   the scene, rather than falling back to a flat block of colour. */
body.no-webgl {
  background:
    radial-gradient(90rem 60rem at 68% 18%, color-mix(in srgb, var(--accent) 12%, transparent), transparent 62%),
    radial-gradient(70rem 50rem at 12% 72%, color-mix(in srgb, var(--navy) 55%, transparent), transparent 60%),
    var(--bg);
}