/* transitions.dev: accordion expand. Source recorded in docs/design-notes.md. */
:root {
  --acc-expand: 250ms;
  --acc-collapse: 250ms;
  --acc-chevron: 250ms;
  --acc-ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* grid-template-rows 0fr → 1fr gives a clean height animation
   with no JS measurement; the inner element clips overflow. */
.t-acc-panel {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows var(--acc-collapse) var(--acc-ease);
}
.t-acc[data-open="true"] .t-acc-panel {
  grid-template-rows: 1fr;
  transition: grid-template-rows var(--acc-expand) var(--acc-ease);
}
.t-acc-panel-inner {
  overflow: hidden;
  opacity: 0;
  filter: blur(2px);
  transition:
    opacity var(--acc-collapse) var(--acc-ease),
    filter var(--acc-collapse) var(--acc-ease);
}
.t-acc[data-open="true"] .t-acc-panel-inner {
  opacity: 1;
  filter: blur(0);
  transition:
    opacity var(--acc-expand) var(--acc-ease),
    filter var(--acc-expand) var(--acc-ease);
}
/* Flip the chevron vertically to turn the "v" into a "^".
   scaleY(-1) about the centre passes through a flat line at
   the midpoint (same look as a `d:` path morph) but animates
   in every browser, unlike CSS `d:` morphing (Chromium only).
   The chevron path is symmetric about the 16x16 viewBox
   centre, so the flip lands exactly on the "^"; non-scaling
   -stroke keeps the stroke width constant through the flip. */
.t-acc-chevron {
  display: inline-flex;
  transform: scaleY(1);
  transform-origin: center;
  transition: transform var(--acc-chevron) var(--acc-ease);
}
.t-acc-chevron path { vector-effect: non-scaling-stroke; }
.t-acc[data-open="true"] .t-acc-chevron {
  transform: scaleY(-1);
}

@media (prefers-reduced-motion: reduce) {
  .t-acc-panel, .t-acc-panel-inner, .t-acc-chevron {
    transition: none !important;
  }
}