/* ============================================================================
   Nav — sticky 72, internal vs external clusters, mega-menu, mobile drawer
   ========================================================================== */

.site-nav {
  position: sticky;
  top: 0;
  z-index: var(--z-nav);
  background: var(--nav-bg);
  border-bottom: 1px solid var(--color-border-subtle);
  backdrop-filter: blur(16px) saturate(160%);
  -webkit-backdrop-filter: blur(16px) saturate(160%);
}

.site-nav__inner {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
  height: var(--nav-h);
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  flex-shrink: 0;
}
.nav-brand__mark {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
}
.nav-brand__word {
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.04em;
  text-transform: lowercase;
  color: var(--color-text-primary);
}
.nav-brand__dot {
  color: var(--color-accent);
  margin-left: 1px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  margin-left: auto;
}

.nav-links__internal,
.nav-links__external {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.nav-links__item {
  position: relative;
}

.nav-links__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 0.625rem 0.875rem;
  font-size: var(--fs-nav);
  font-weight: 500;
  line-height: 1;
  color: var(--color-text-secondary);
  border-radius: var(--radius-md);
  transition: color var(--duration-fast) var(--ease-out);
  position: relative;
}
.nav-links__link--external {
  font-family: var(--font-mono);
  font-size: var(--fs-nav-external);
  font-weight: 400;
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
  gap: 0.4rem;
}
.nav-links__icon {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  opacity: 0.9;
  color: currentColor;
}
.nav-links__link--external .icon {
  width: 12px;
  height: 12px;
  flex-shrink: 0;
  opacity: 0.7;
  color: currentColor;
}
.nav-links__link--external:hover .nav-links__icon,
.nav-links__link--external:hover .icon {
  opacity: 1;
  color: var(--color-accent);
}
.nav-links__label {
  line-height: 1;
}

.nav-links__link:hover {
  color: var(--color-text-primary);
}

.nav-links__link.is-active {
  color: var(--color-text-primary);
}
.nav-links__link.is-active::after {
  content: "";
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: -4px;
  height: 2px;
  background: var(--color-accent);
  border-radius: 1px;
}

.nav-divider {
  display: inline-block;
  width: 1px;
  height: 18px;
  background: var(--color-border-strong);
  flex-shrink: 0;
}

.nav-cta {
  margin-left: var(--space-2);
  flex-shrink: 0;
  font-size: 0.9375rem;
  padding: 0.65rem 1.15rem;
}

/* ---- Mega-menu ---- */
.nav-links__item--has-mega > .nav-links__link::after {
  content: "";
  display: inline-block;
  margin-left: var(--space-1);
  width: 6px;
  height: 6px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(45deg) translate(-1px, -2px);
  opacity: 0.6;
  transition: transform var(--duration-fast) var(--ease-out);
}

.nav-links__item--has-mega.is-open > .nav-links__link::after {
  transform: rotate(-135deg) translate(-1px, 1px);
}

.mega-menu {
  position: absolute;
  top: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) translateY(-4px);
  min-width: 720px;
  background: var(--color-surface-elevated);
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--inner-highlight), 0 16px 40px rgba(0, 0, 0, 0.4);
  padding: var(--space-5);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-fast) var(--ease-out), transform var(--duration-fast) var(--ease-out);
  z-index: var(--z-mega);
}
.nav-links__item--has-mega.is-open .mega-menu {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
  pointer-events: auto;
}
/* Show via [hidden] removal by JS */
.mega-menu[hidden] {
  display: none;
}

.mega-menu__inner {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: var(--space-5);
}
.mega-menu__group-label {
  font-family: var(--font-mono);
  font-size: var(--fs-label);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: var(--space-3);
}
.mega-menu__list {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}
.mega-menu__link {
  display: block;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  transition: background var(--duration-fast) var(--ease-out);
}
.mega-menu__link:hover {
  background: var(--color-surface-interactive);
}
.mega-menu__title {
  display: block;
  font-size: var(--fs-body-sm);
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: 2px;
}
.mega-menu__sub {
  display: block;
  font-size: var(--fs-caption);
  color: var(--color-text-muted);
  line-height: 1.4;
}
.mega-menu__all {
  display: inline-block;
  margin-top: var(--space-4);
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-border-subtle);
  font-size: var(--fs-body-sm);
  font-weight: 500;
  color: var(--color-accent);
}

/* ---- Mobile toggle (≤860) ---- */
.nav-toggle {
  display: none;
  margin-left: auto;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 4px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border-strong);
  background: var(--color-surface-elevated);
}
.nav-toggle__bar {
  display: block;
  width: 18px;
  height: 1.5px;
  background: var(--color-text-primary);
  transition: transform var(--duration-fast) var(--ease-out), opacity var(--duration-fast) var(--ease-out);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
  transform: translateY(5.5px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
  transform: translateY(-5.5px) rotate(-45deg);
}

/* ---- Mobile drawer ---- */
.nav-drawer {
  position: fixed;
  top: var(--nav-h);
  right: 0;
  bottom: 0;
  width: min(420px, 100%);
  background: var(--color-surface);
  border-left: 1px solid var(--color-border-strong);
  padding: var(--space-6);
  overflow-y: auto;
  z-index: var(--z-drawer);
  transform: translateX(100%);
  transition: transform var(--duration-base) var(--ease-out);
  box-shadow: -16px 0 40px rgba(0, 0, 0, 0.4);
}
.nav-drawer.is-open {
  transform: translateX(0);
}
.nav-drawer[hidden] {
  display: none;
}
.nav-drawer__section {
  margin-bottom: var(--space-6);
}
.nav-drawer__label {
  font-family: var(--font-mono);
  font-size: var(--fs-label);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: var(--space-2);
}
.nav-drawer__section ul {
  display: flex;
  flex-direction: column;
}
.nav-drawer__link {
  display: flex;
  align-items: center;
  min-height: 44px;
  padding: var(--space-3) 0;
  font-size: var(--fs-body);
  font-weight: 500;
  color: var(--color-text-primary);
  border-bottom: 1px solid var(--color-border-subtle);
}
.nav-drawer__cta {
  width: 100%;
  margin-top: var(--space-4);
  justify-content: center;
}
.nav-drawer__backdrop {
  position: fixed;
  inset: var(--nav-h) 0 0 0;
  background: rgba(7, 9, 15, 0.65);
  backdrop-filter: blur(2px);
  -webkit-backdrop-filter: blur(2px);
  z-index: calc(var(--z-drawer) - 1);
  opacity: 0;
  transition: opacity var(--duration-base) var(--ease-out);
}
.nav-drawer__backdrop.is-open {
  opacity: 1;
}
.nav-drawer__backdrop[hidden] {
  display: none;
}

body.nav-drawer-open {
  overflow: hidden;
}

/* ---- Responsive (≤860) ---- */
@media (max-width: 860px) {
  .nav-toggle {
    display: inline-flex;
  }
  .nav-links,
  .nav-divider,
  .nav-cta {
    display: none;
  }
}

/* ---- Responsive: hide mega-menu columns on narrow desktop ---- */
@media (max-width: 1100px) {
  .mega-menu {
    min-width: 600px;
  }
}