/* ============================================================================
   f(x) → NATURE DS — Navigation bundle [06]
   Breadcrumb, Pagination (reuse), Tabs (reuse), Navigation Menu, Accordion
   (reuse .fd-collapse), Collapsible (reuse), Separator.
   Consumes ONLY tokens from styles/tokens.css. All classes prefixed .fd-.
   brutalist: hairline borders, sharp corners, mono technical labels,
   acid-lime accent. Dark default + [data-theme="light"] correct.

   NOTE on reuse:
     · Pagination styles live in components/data.css (.fd-pagination).
     · Tabs + Collapse/Accordion (.fd-tabs, .fd-tabs--boxed, .fd-accordion,
       .fd-collapse) were migrated INTO this file from the retired surfaces.css.
   This file also adds the new components for this section: Breadcrumb,
   Navigation Menu, Separator — plus a couple of additive tab/accordion
   helpers used by the examples here.
   ============================================================================ */

/* ============================================================================
   BREADCRUMB — .fd-breadcrumb
   A wayfinding trail: mono links, slash/chevron separators, current page marker.
   ============================================================================ */
.fd-breadcrumb {
  width: 100%;
}
.fd-breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
  margin: 0;
  padding: 0;
  list-style: none;
}
.fd-breadcrumb__item {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
}
.fd-breadcrumb__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  text-decoration: none;
  color: var(--foreground-muted);
  border-bottom: var(--border-width) solid transparent;
  transition: color var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out);
}
.fd-breadcrumb__link:hover {
  color: var(--foreground);
  border-bottom-color: var(--accent);
}
.fd-breadcrumb__link:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.fd-breadcrumb__link svg {
  width: 13px;
  height: 13px;
  color: var(--foreground-subtle);
}
.fd-breadcrumb__link:hover svg { color: var(--accent-text); }

/* the current (active) crumb — not a link */
.fd-breadcrumb__current {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  color: var(--foreground);
}

/* separators: slash glyph (default) + chevron variant */
.fd-breadcrumb__sep {
  display: inline-flex;
  align-items: center;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--foreground-faint);
  user-select: none;
}
.fd-breadcrumb__sep svg {
  width: 12px;
  height: 12px;
}

/* ellipsis / collapsed segment */
.fd-breadcrumb__ellipsis {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 22px;
  height: 22px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wide);
  color: var(--foreground-subtle);
  background: var(--surface-2);
  border: var(--border-width) solid var(--border);
  border-radius: var(--radius-sm);
}

/* ============================================================================
   NAVIGATION MENU — .fd-navmenu  (CSS-only hover/focus-within reveal)
   A horizontal menu bar whose triggers reveal rich dropdown panels on hover
   or keyboard focus. No JS — pure :hover / :focus-within.
   ============================================================================ */
.fd-navmenu {
  position: relative;
  display: inline-block;
}
.fd-navmenu__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  padding: var(--space-1);
  list-style: none;
  background: var(--surface);
  border: var(--border-width) solid var(--border);
}
.fd-navmenu__item {
  position: relative;
}
.fd-navmenu__trigger,
.fd-navmenu__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  text-decoration: none;
  color: var(--foreground-muted);
  background: transparent;
  border: var(--border-width) solid transparent;
  border-radius: var(--radius-none);
  cursor: pointer;
  transition: color var(--duration-fast) var(--ease-out),
    background var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out);
}
.fd-navmenu__trigger svg {
  width: 11px;
  height: 11px;
  color: var(--foreground-subtle);
  transition: transform var(--duration-base) var(--ease-out),
    color var(--duration-fast) var(--ease-out);
}
.fd-navmenu__trigger:hover,
.fd-navmenu__link:hover,
.fd-navmenu__item:focus-within > .fd-navmenu__trigger {
  color: var(--foreground);
  background: var(--surface-2);
  border-color: var(--border);
}
.fd-navmenu__item:hover > .fd-navmenu__trigger svg,
.fd-navmenu__item:focus-within > .fd-navmenu__trigger svg {
  transform: rotate(180deg);
  color: var(--accent-text);
}
.fd-navmenu__trigger:focus-visible,
.fd-navmenu__link:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

/* the reveal panel */
.fd-navmenu__panel {
  position: absolute;
  top: calc(100% + var(--space-2));
  left: 0;
  z-index: var(--z-dropdown);
  min-width: 320px;
  padding: var(--space-3);
  background: var(--surface);
  border: var(--border-width) solid var(--border-strong);
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity var(--duration-fast) var(--ease-out),
    transform var(--duration-fast) var(--ease-out),
    visibility 0s linear var(--duration-fast);
}
.fd-navmenu__item:hover > .fd-navmenu__panel,
.fd-navmenu__item:focus-within > .fd-navmenu__panel {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  transition: opacity var(--duration-fast) var(--ease-out),
    transform var(--duration-fast) var(--ease-out);
}
/* align last item's panel to the right so it never clips off-edge */
.fd-navmenu__item:last-child > .fd-navmenu__panel {
  left: auto;
  right: 0;
}

/* panel contents: a grid of rich link rows */
.fd-navmenu__grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-2);
}
.fd-navmenu__grid--1 { grid-template-columns: 1fr; }
.fd-navmenu__panel-link {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding: var(--space-3);
  text-decoration: none;
  background: var(--background-subtle);
  border: var(--border-width) solid var(--border);
  transition: border-color var(--duration-fast) var(--ease-out),
    background var(--duration-fast) var(--ease-out);
}
.fd-navmenu__panel-link:hover,
.fd-navmenu__panel-link:focus-visible {
  border-color: var(--accent-border);
  background: var(--surface-2);
  outline: none;
}
.fd-navmenu__panel-title {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  color: var(--foreground);
}
.fd-navmenu__panel-link:hover .fd-navmenu__panel-title { color: var(--accent-text); }
.fd-navmenu__panel-desc {
  font-size: var(--text-xs);
  line-height: var(--leading-normal);
  color: var(--foreground-muted);
}
.fd-navmenu__panel-kbd {
  font-family: var(--font-mono);
  font-size: var(--text-2xs);
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: var(--accent-text);
}

/* a simple stacked list inside a panel */
.fd-navmenu__panel-list {
  display: flex;
  flex-direction: column;
  margin: 0;
  padding: 0;
  list-style: none;
}
.fd-navmenu__panel-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-2) var(--space-3);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  text-decoration: none;
  color: var(--foreground-muted);
  border: var(--border-width) solid transparent;
  transition: color var(--duration-fast) var(--ease-out),
    background var(--duration-fast) var(--ease-out);
}
.fd-navmenu__panel-item:hover,
.fd-navmenu__panel-item:focus-visible {
  color: var(--foreground);
  background: var(--surface-2);
  outline: none;
}
.fd-navmenu__panel-item .fd-navmenu__panel-kbd { margin-left: auto; }

/* responsive: navmenu panels become full-width stacks */
@media (max-width: 600px) {
  .fd-navmenu__panel {
    min-width: min(320px, 86vw);
  }
  .fd-navmenu__grid {
    grid-template-columns: 1fr;
  }
}

/* ============================================================================
   TABS — .fd-tabs  (hooks: data-fd-tab / data-fd-tab-panel / is-active)
   Base primitive (migrated from the retired surfaces bundle).
   ============================================================================ */
.fd-tabs { width: 100%; max-width: 560px; }
.fd-tabs__list {
  display: flex;
  gap: var(--space-1);
  border-bottom: var(--border-width) solid var(--border);
}
.fd-tabs__trigger {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-4);
  margin-bottom: calc(-1 * var(--border-width));
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: var(--foreground-subtle);
  background: transparent;
  border: 0;
  border-bottom: var(--border-width-thick) solid transparent;
  cursor: pointer;
  transition: color var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out);
}
.fd-tabs__trigger:hover { color: var(--foreground-muted); }
.fd-tabs__trigger .fd-tabs__idx { color: var(--foreground-faint); }
.fd-tabs__trigger.is-active {
  color: var(--foreground);
  border-bottom-color: var(--accent);
}
.fd-tabs__trigger.is-active .fd-tabs__idx { color: var(--accent-text); }
.fd-tabs__panels { padding: var(--space-5) var(--space-1); }
.fd-tabs__panel {
  display: none;
  color: var(--foreground-muted);
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
  animation: fd-tab-in var(--duration-base) var(--ease-out);
}
.fd-tabs__panel.is-active { display: block; }
.fd-tabs__panel h4 {
  margin-bottom: var(--space-2);
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  color: var(--foreground);
}
@keyframes fd-tab-in {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}
/* Boxed tabs variant */
.fd-tabs--boxed .fd-tabs__list {
  gap: 0;
  padding: var(--space-1);
  background: var(--background-subtle);
  border: var(--border-width) solid var(--border);
}
.fd-tabs--boxed .fd-tabs__trigger { margin-bottom: 0; border-bottom: 0; }
.fd-tabs--boxed .fd-tabs__trigger.is-active {
  color: var(--on-accent);
  background: var(--accent);
}
.fd-tabs--boxed .fd-tabs__trigger.is-active .fd-tabs__idx { color: var(--on-accent); }

/* ============================================================================
   ACCORDION / COLLAPSE — .fd-accordion + .fd-collapse
   Base primitive (migrated from the retired surfaces bundle).
   Hooks: data-fd-collapse-trigger / is-open.
   ============================================================================ */
.fd-accordion {
  width: 100%;
  max-width: 560px;
  border: var(--border-width) solid var(--border);
  background: var(--surface);
}
.fd-collapse { border-top: var(--border-width) solid var(--border); }
.fd-accordion > .fd-collapse:first-child { border-top: 0; }
.fd-collapse__trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  width: 100%;
  padding: var(--space-4) var(--space-5);
  font-family: var(--font-display);
  font-size: var(--text-base);
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  text-align: left;
  color: var(--foreground);
  background: transparent;
  border: 0;
  cursor: pointer;
  transition: background var(--duration-fast) var(--ease-out);
}
.fd-collapse__trigger:hover { background: var(--background-subtle); }
.fd-collapse__trigger-label {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
}
.fd-collapse__idx {
  font-family: var(--font-mono);
  font-size: var(--text-2xs);
  font-weight: var(--weight-medium);
  letter-spacing: var(--tracking-label);
  color: var(--accent-text);
}
.fd-collapse__chevron {
  flex-shrink: 0;
  width: 16px;
  height: 16px;
  color: var(--foreground-subtle);
  transition: transform var(--duration-base) var(--ease-out),
    color var(--duration-fast) var(--ease-out);
}
.fd-collapse__trigger[aria-expanded="true"] .fd-collapse__chevron {
  transform: rotate(180deg);
  color: var(--accent-text);
}
.fd-collapse__body {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows var(--duration-base) var(--ease-out);
}
.fd-collapse.is-open .fd-collapse__body { grid-template-rows: 1fr; }
.fd-collapse__body-inner {
  overflow: hidden;
  color: var(--foreground-muted);
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
}
.fd-collapse.is-open .fd-collapse__body-inner {
  padding: 0 var(--space-5) var(--space-5);
}

/* ============================================================================
   ACCORDION — additive helper: flush, borderless variant used in an example.
   ============================================================================ */
.fd-accordion--flush {
  border-left: 0;
  border-right: 0;
  background: transparent;
}
.fd-accordion--flush > .fd-collapse:first-child {
  border-top: 0;
}

/* ============================================================================
   COLLAPSIBLE — additive helper (a single bordered disclosure, .fd-collapse)
   Wrap a lone .fd-collapse to give it its own hairline frame outside an
   accordion stack.
   ============================================================================ */
.fd-collapsible {
  width: 100%;
  max-width: 560px;
  border: var(--border-width) solid var(--border);
  background: var(--surface);
}
.fd-collapsible > .fd-collapse {
  border-top: 0;
}

/* ============================================================================
   SEPARATOR — .fd-separator (horizontal default) + --vertical + labelled
   ============================================================================ */
.fd-separator {
  width: 100%;
  height: var(--border-width);
  margin: 0;
  border: 0;
  background: var(--border);
}
.fd-separator--strong { background: var(--border-strong); }
.fd-separator--accent { background: var(--accent); }
.fd-separator--dashed {
  height: 0;
  background: transparent;
  border-top: var(--border-width) dashed var(--border);
}

/* vertical: stretches to the height of a flex row */
.fd-separator--vertical {
  width: var(--border-width);
  height: auto;
  min-height: 1.2em;
  align-self: stretch;
}
.fd-separator--vertical.fd-separator--strong { background: var(--border-strong); }
.fd-separator--vertical.fd-separator--accent { background: var(--accent); }

/* a horizontal separator with a centered mono label (registration motif) */
.fd-separator-text {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  width: 100%;
  font-family: var(--font-mono);
  font-size: var(--text-2xs);
  font-weight: var(--weight-medium);
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: var(--foreground-subtle);
}
.fd-separator-text::before,
.fd-separator-text::after {
  content: "";
  flex: 1 1 auto;
  height: var(--border-width);
  background: var(--border);
}

/* a small inline-row helper so separator examples can lay out cleanly */
.fd-sep-row {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  color: var(--foreground-muted);
}