/* ============================================================
   topnav.css  —  Horizontal top navigation with nested dropdowns
   Depth 0: bar items.  Depth 1+: dropdown panels (stack vertically).
   Sub-dropdowns at depth 1+ open to the RIGHT (flyout).
   ============================================================ */

.topnav {
  height: var(--topnav-h);
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: var(--header-h);
  z-index: 90;
  /* MUST be overflow:visible so dropdowns are not clipped by this element.
     Horizontal scroll is delegated to .topnav-inner below. */
  overflow: visible;
  transition: background var(--dur2) var(--ease), border-color var(--dur2) var(--ease);
}

.topnav-inner {
  height: 100%;
  padding: 0 1.375rem;
  display: flex; align-items: center; gap: 0.125rem;
  /* NOTE: Setting overflow-x:auto here forces overflow-y:auto too (browser spec),
     which would clip the dropdowns. We instead allow natural overflow and accept
     that very long navs wrap — acceptable for a docs site. */
  overflow: visible;
  white-space: nowrap;
}

/* ── Depth-0 plain link ──────────────────────────────────── */
.tn-link {
  display: inline-flex; align-items: center;
  padding: 0.3rem 0.7rem;
  border-radius: var(--r);
  font-size: 0.83rem; font-weight: 500;
  color: var(--fg2); white-space: nowrap;
  border: 1px solid transparent;
  transition: all var(--dur) var(--ease);
}
.tn-link:hover  { color: var(--fg); background: color-mix(in srgb, var(--fg) 7%, transparent); filter: none; }
.tn-link.active { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 35%, transparent); }

/* ── Item wrapper (any depth) ────────────────────────────── */
.tn-item { position: relative; }

/* ── Dropdown trigger button (any depth) ─────────────────── */
.tn-btn {
  display: inline-flex; align-items: center; gap: 0.3rem;
  padding: 0.3rem 0.7rem;
  border-radius: var(--r);
  font-size: 0.83rem; font-weight: 500;
  color: var(--fg2); white-space: nowrap;
  background: none; border: 1px solid transparent;
  transition: all var(--dur) var(--ease);
}
.tn-btn:hover  { color: var(--fg); background: color-mix(in srgb, var(--fg) 7%, transparent); }
.tn-btn.active { color: var(--accent); }

/* Chevron spins when open */
.tn-chevron {
  width: 12px; height: 12px; flex-shrink: 0;
  transition: transform var(--dur) var(--ease);
}
.tn-item.is-open > .tn-btn .tn-chevron { transform: rotate(180deg); }

/* ── Dropdown panel ──────────────────────────────────────── */
/* depth 0 → opens downward
   depth 1+ → flies out to the right */
.tn-dropdown {
  position: absolute;
  min-width: 192px;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--r2);
  box-shadow: var(--shadow);
  padding: 0.375rem;
  z-index: 400;           /* well above topnav z-index:90 */
  /* hidden */
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity var(--dur) var(--ease),
              visibility var(--dur) var(--ease),
              transform var(--dur) var(--ease);
  /* depth 0: drop down */
  top: calc(100% + 4px); left: 0;
  transform: translateY(-4px);
}

/* depth 1+: fly right */
.tn-dropdown[data-depth="1"],
.tn-dropdown[data-depth="2"],
.tn-dropdown[data-depth="3"],
.tn-dropdown[data-depth="4"],
.tn-dropdown[data-depth="5"] {
  top: -0.375rem;
  left: calc(100% + 4px);
  transform: translateX(-4px);
}

/* open state */
.tn-item.is-open > .tn-dropdown {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translateY(0) translateX(0);
}

/* ── Links inside dropdown ───────────────────────────────── */
.tn-drop-link {
  display: block;
  padding: 0.4rem 0.75rem;
  border-radius: var(--r);
  font-size: 0.83rem; color: var(--fg2);
  white-space: nowrap;
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}
.tn-drop-link:hover  { color: var(--fg); background: color-mix(in srgb, var(--fg) 7%, transparent); filter: none; }
.tn-drop-link.active { color: var(--accent); font-weight: 600; }

/* Nested .tn-item inside a dropdown */
.tn-dropdown .tn-item { display: block; }
.tn-dropdown .tn-btn {
  width: 100%; text-align: left;
  padding: 0.4rem 0.75rem;
  font-size: 0.83rem;
  justify-content: space-between;
}
/* Nested chevrons point right instead of down */
.tn-dropdown .tn-chevron          { transform: rotate(-90deg); }
.tn-dropdown .tn-item.is-open > .tn-btn .tn-chevron { transform: rotate(90deg); }

/* ── Mobile: stack vertically, no flyout ────────────────── */
@media (max-width: 768px) {
  .topnav { height: auto; min-height: var(--topnav-h); overflow: visible; }
  .topnav-inner { flex-wrap: wrap; white-space: normal; height: auto; padding: 0.25rem 0.875rem; gap: 0; overflow: visible; }

  /* All dropdowns become max-height animated vertically */
  .tn-dropdown,
  .tn-dropdown[data-depth="1"],
  .tn-dropdown[data-depth="2"],
  .tn-dropdown[data-depth="3"],
  .tn-dropdown[data-depth="4"],
  .tn-dropdown[data-depth="5"] {
    position: static;
    box-shadow: none;
    border: none; border-radius: 0;
    padding: 0;
    background: transparent;
    transform: none !important;
    max-height: 0;
    overflow: hidden;
    display: block;
    opacity: 1; visibility: visible; pointer-events: auto;
    transition: max-height var(--dur2) var(--ease);
  }
  .tn-item.is-open > .tn-dropdown { max-height: 600px; }

  .tn-dropdown .tn-drop-link,
  .tn-dropdown .tn-btn              { padding-left: 1.5rem; }
  .tn-dropdown .tn-dropdown .tn-drop-link,
  .tn-dropdown .tn-dropdown .tn-btn { padding-left: 2.25rem; }
  .tn-dropdown .tn-dropdown .tn-dropdown .tn-drop-link,
  .tn-dropdown .tn-dropdown .tn-dropdown .tn-btn { padding-left: 3rem; }

  /* Nested chevrons point down again on mobile */
  .tn-dropdown .tn-chevron { transform: none; }
  .tn-dropdown .tn-item.is-open > .tn-btn .tn-chevron { transform: rotate(180deg); }
}