/* ============================================================================
   DIAGRAM — stage, view chrome, tier panel
   ========================================================================== */

.stage {
  position: relative;
  width: 100%;
  aspect-ratio: 4 / 3;
  max-height: 68vh;
  /* Slightly deeper than the hero gradient. The car is a dark graphite, so
     this stays light — the separation comes from the value gap, and it is
     the same pale ground the frames were rendered against. */
  background: linear-gradient(172deg, #e7edf1 0%, #eff2f3 44%, #dfe6ea 100%);
  overflow: hidden;

  /* THE most important line in this file.
     `pan-y` tells the browser vertical scrolling is never ours to intercept,
     so it stays on the compositor thread and cannot be janked by our JS.
     Never `none` on a full-width element — it traps page scroll. */
  touch-action: pan-y;
  overscroll-behavior-y: contain;
}
@media (min-width: 760px) {
  .stage { aspect-ratio: 16 / 9; }
}

.stage__canvas {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  display: block;
  cursor: grab;
  touch-action: inherit;
}
.stage[data-dragging='true'] .stage__canvas { cursor: grabbing; }

/* Pre-rendered still — frame 9 of the same sequence, so the swap to the
   canvas is invisible. Visible until the first frame decodes, and permanently
   if JS never runs. It is the fallback, not a spinner. */
.stage__still {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  transition: opacity var(--dur-slow) var(--ease);
}
.stage[data-ready='true'] .stage__still {
  opacity: 0;
  pointer-events: none;
}

/* Bottom-right, not centred — centred puts it straight on top of the car. */
.stage__hint {
  position: absolute;
  inset-block-end: 12px;
  inset-inline-end: 12px;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 9px 16px;
  border-radius: var(--radius-pill);
  background: rgba(0, 13, 16, 0.72);
  color: #fff;
  font-size: 0.8125rem;
  font-weight: var(--weight-bold);
  letter-spacing: 0.03em;
  white-space: nowrap;
  pointer-events: none;
  transition: opacity var(--dur) var(--ease);
}
.stage[data-touched='true'] .stage__hint { opacity: 0; }

.stage__fallback-note {
  position: absolute;
  inset-block-end: 0;
  inset-inline: 0;
  padding: var(--space-sm);
  text-align: center;
  font-size: var(--text-caption);
  color: var(--text-muted);
  background: rgba(255, 255, 255, 0.86);
}

/* ── View chrome ──────────────────────────────────────────────────────── */

.views {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-block-start: var(--space-md);
}
.views__btn {
  border: 1px solid var(--border-hairline);
  background: transparent;
  color: var(--text-primary);
  font: inherit;
  font-size: 0.9375rem;
  font-weight: var(--weight-bold);
  padding: 10px 17px;
  border-radius: var(--radius-pill);
  cursor: pointer;
  min-height: 44px;
  transition: background var(--dur) var(--ease),
              color var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}
.views__btn:hover { border-color: var(--color-deep-ink); }
.views__btn[aria-pressed='true'] {
  background: var(--color-deep-ink);
  color: var(--color-pure-white);
  border-color: var(--color-deep-ink);
}

/* ── Tier panel ───────────────────────────────────────────────────────── */

.zone-panel {
  margin-block-start: var(--space-md);
  border-block-start: 3px solid var(--panel-swatch, var(--color-deep-ink));
  padding-block-start: var(--space-sm);
  display: grid;
  gap: 10px;
  min-height: 132px;
  align-content: start;
}
.zone-panel[data-tier='hero']  { --panel-swatch: var(--tier-hero); }
.zone-panel[data-tier='mid']   { --panel-swatch: var(--tier-mid); }
.zone-panel[data-tier='small'] { --panel-swatch: var(--tier-small); }

.zone-panel__empty { color: var(--text-muted); margin: 0; max-width: 46ch; }

.zone-panel__top {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-sm);
}
.zone-panel__tier {
  font-size: var(--text-caption);
  font-weight: var(--weight-bold);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);   /* the selected zone is the page's one clay element */
}
.zone-panel__desc { color: var(--text-muted); margin: 0; max-width: 52ch; }
.zone-panel__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  font-size: var(--text-caption);
  color: var(--text-muted);
}
.zone-panel__meta strong {
  color: var(--text-primary);
  font-weight: var(--weight-bold);
}

@media (min-width: 900px) {
  .diagram-grid {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 340px);
    gap: var(--space-xl);
    align-items: start;
  }
  .zone-panel { margin-block-start: 0; }
}