/* ─────────────────────────────────────────────
   _collapse.css — Collapse & Accordion
   ─────────────────────────────────────────────
   API:
     <div class="collapse">
       <div class="collapse-header" onclick="collapseToggle(this)">Title <span class="collapse-icon"></span></div>
       <div class="collapse-body">Content</div>
     </div>

     <details class="collapse">
       <summary class="collapse-header">Title <span class="collapse-icon"></span></summary>
       <div class="collapse-body">Content</div>
     </details>

   Modifiers: .collapse-plus  .collapse-ghost  .collapse-primary
   Wrappers:  .accordion  .accordion-flush
───────────────────────────────────────────── */

/* ═══════════════════════════════
   BASE
═══════════════════════════════ */
.collapse {
  border: 1px solid color-mix(in srgb, var(--color-neutral-600) 25%, transparent);
  border-radius: var(--radius-lg, 12px);
  overflow: hidden;
  transition: border-color 0.22s;
  background: var(--color-dark-secondary);
}

.collapse + .collapse {
  margin-top: 8px;
}

/* ═══════════════════════════════
   HEADER
═══════════════════════════════ */
.collapse-header,
details.collapse > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 18px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-light);
  background: transparent;
  border: none;
  width: 100%;
  text-align: left;
  list-style: none;
  transition: background 0.2s, color 0.2s;
  user-select: none;
}

/* Remove native arrow */
.collapse-header::-webkit-details-marker,
details.collapse > summary::-webkit-details-marker {
  display: none;
}

.collapse-header:hover,
details.collapse > summary:hover {
  color: var(--color-primary);
  background: color-mix(in srgb, var(--color-primary) 5%, transparent);
}

/* ═══════════════════════════════
   CHEVRON ICON
═══════════════════════════════ */
.collapse-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  position: relative;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  opacity: 0.7;
}

.collapse-icon::before,
.collapse-icon::after {
  content: '';
  position: absolute;
  top: 50%;
  width: 10px;
  height: 1.5px;
  background: currentColor;
  border-radius: 2px;
}

.collapse-icon::before { left: 2px;  transform: translateY(-50%) rotate(45deg); }
.collapse-icon::after  { right: 2px; transform: translateY(-50%) rotate(-45deg); }

.collapse.is-open .collapse-icon,
details.collapse[open] .collapse-icon {
  transform: rotate(180deg);
}

/* ═══════════════════════════════
   PLUS/MINUS ICON
═══════════════════════════════ */
.collapse-plus .collapse-icon::before {
  width: 12px;
  left: 50%;
  transform: translate(-50%, -50%);
}

.collapse-plus .collapse-icon::after {
  width: 1.5px;
  height: 12px;
  right: auto;
  left: 50%;
  transform: translate(-50%, -50%);
  transition: transform 0.3s, opacity 0.3s;
}

.collapse-plus.is-open .collapse-icon::before,
details.collapse-plus[open] .collapse-icon::before {
  transform: translate(-50%, -50%);
}

.collapse-plus.is-open .collapse-icon::after,
details.collapse-plus[open] .collapse-icon::after {
  opacity: 0;
  transform: translate(-50%, -50%) rotate(90deg);
}

/* ═══════════════════════════════
   BODY
═══════════════════════════════ */
.collapse-body {
  max-height: 0;
  overflow: hidden;
  padding: 0 18px;
  font-size: 14px;
  color: var(--color-muted);
  line-height: 1.75;
  border-top: 1px solid transparent;
  transition:
    max-height 0.35s cubic-bezier(0.4, 0, 0.2, 1),
    padding    0.35s cubic-bezier(0.4, 0, 0.2, 1),
    border-color 0.22s;
}

/* JS toggle */
.collapse.is-open > .collapse-body {
  max-height: 600px;
  padding: 16px 18px;
  border-top-color: color-mix(in srgb, var(--color-neutral-600) 18%, transparent);
}

/* Native details */
details.collapse .collapse-body {
  max-height: 0;
  overflow: hidden;
  padding: 0 18px;
  transition:
    max-height 0.35s cubic-bezier(0.4, 0, 0.2, 1),
    padding    0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

details.collapse[open] .collapse-body {
  max-height: 600px;
  padding: 16px 18px;
  border-top: 1px solid color-mix(in srgb, var(--color-neutral-600) 18%, transparent);
}

/* ═══════════════════════════════
   OPEN STATE
═══════════════════════════════ */
.collapse.is-open,
details.collapse[open] {
  border-color: color-mix(in srgb, var(--color-primary) 28%, transparent);
}

.collapse.is-open > .collapse-header,
details.collapse[open] > summary {
  color: var(--color-primary);
  background: color-mix(in srgb, var(--color-primary) 7%, transparent);
}

/* ═══════════════════════════════
   VARIANT: GHOST
═══════════════════════════════ */
.collapse-ghost {
  border-color: transparent;
  background: transparent;
}

.collapse-ghost.is-open,
details.collapse-ghost[open] {
  border-color: transparent;
  background: transparent;
}

.collapse-ghost.is-open > .collapse-body {
  border-top-color: color-mix(in srgb, var(--color-neutral-600) 18%, transparent);
}

/* ═══════════════════════════════
   VARIANT: PRIMARY
═══════════════════════════════ */
.collapse-primary {
  border-color: color-mix(in srgb, var(--color-primary) 30%, transparent);
  background: color-mix(in srgb, var(--color-primary) 4%, var(--color-dark-secondary));
}

.collapse-primary > .collapse-header,
details.collapse-primary > summary {
  color: var(--color-primary);
}

.collapse-primary.is-open > .collapse-header,
details.collapse-primary[open] > summary {
  background: color-mix(in srgb, var(--color-primary) 12%, transparent);
}

.collapse-primary.is-open > .collapse-body {
  border-top-color: color-mix(in srgb, var(--color-primary) 20%, transparent);
}

/* ═══════════════════════════════
   ACCORDION WRAPPER
═══════════════════════════════ */
.accordion > .collapse + .collapse {
  margin-top: 6px;
}

/* ─── Flush (connected) ─── */
.accordion-flush {
  border: 1px solid color-mix(in srgb, var(--color-neutral-600) 22%, transparent);
  border-radius: var(--radius-lg, 12px);
  overflow: hidden;
}

.accordion-flush > .collapse {
  border: none;
  border-radius: 0;
  margin-top: 0;
}

.accordion-flush > .collapse + .collapse {
  border-top: 1px solid color-mix(in srgb, var(--color-neutral-600) 18%, transparent);
}

.accordion-flush > .collapse.is-open,
.accordion-flush > details.collapse[open] {
  border-color: transparent;
  background: color-mix(in srgb, var(--color-primary) 5%, var(--color-dark-secondary));
}