.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--nav-bg);
  backdrop-filter: saturate(140%) blur(12px);
  border-bottom: 1px solid var(--border-hairline);
}

.nav-inner {
  display: flex;
  align-items: center;
  height: 64px;
  gap: 32px;
}

.nav-logo {
  display: inline-flex;
  align-items: center;
  height: 40px;
  padding: 6px 0;
}
.nav-logo-img {
  display: block;
  height: 28px;
  width: auto;
}

.nav-links {
  display: flex;
  gap: 32px;
  margin-inline: auto;
}
.nav-links a {
  color: var(--text-muted);
  font-size: var(--fs-base-sm);
  font-weight: 500;
  padding: 8px 0;
  transition: color var(--t-base);
}
.nav-links a:hover,
.nav-links a[data-active] {
  color: var(--text-base);
}

/* dropdown groups — open state driven by JS (.is-open), single-open at a time */
.nav-link-group {
  position: relative;
  display: inline-flex;
  align-items: center;
}
.nav-link-trigger {
  display: inline-flex;
  align-items: center;
}
.nav-link-trigger::after {
  content: '';
  width: 0;
  height: 0;
  margin-left: 5px;
  border-left: 3.5px solid transparent;
  border-right: 3.5px solid transparent;
  border-top: 4px solid currentColor;
  opacity: 0.45;
  transition: opacity var(--t-base), transform var(--t-base);
}
.nav-link-group.is-open .nav-link-trigger::after {
  opacity: 0.9;
  transform: rotate(180deg);
}

.nav-dropdown {
  position: absolute;
  top: 100%;
  left: 0;                    /* panel sits directly under its trigger */
  padding-top: 8px;           /* hover-bridge between trigger and panel */
  opacity: 0;
  visibility: hidden;
  transform: translateY(-2px);
  transition: opacity var(--t-base), transform var(--t-base), visibility 0s linear var(--t-base);
  z-index: 60;
  pointer-events: none;
}
.nav-link-group.is-open .nav-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  pointer-events: auto;
  transition: opacity var(--t-base), transform var(--t-base);
}
.nav-dropdown-inner {
  width: max-content;
  min-width: 160px;
  background: var(--bg-page);
  border: 1px solid var(--border-divider);
  border-radius: var(--radius);
  padding: 5px;
  box-shadow: 0 8px 24px -12px rgba(0, 0, 0, 0.4);
}
.nav-dropdown-item {
  display: block;
  padding: 10px 16px;
  font-size: var(--fs-base-sm);
  font-weight: 500;
  line-height: var(--lh-tight);
  color: var(--text-muted);
  letter-spacing: -0.005em;
  border-radius: var(--radius);
  transition: background var(--t-base), color var(--t-base);
}
.nav-dropdown-item:hover,
.nav-dropdown-item:focus-visible {
  background: var(--surface-2);
  color: var(--text-strong);
}

/* nested item — child of the row above. Indent via padding (not margin) so
   the hover fill still spans the full row; a hairline tree connector (└)
   carries the hierarchy. */
.nav-dropdown-item.nav-dropdown-depth-1 {
  position: relative;
  padding-left: 28px;
  font-size: var(--fs-sm);
  font-weight: 400;
  color: var(--text-tertiary);
}
.nav-dropdown-item.nav-dropdown-depth-1::before {
  content: '';
  position: absolute;
  left: 13px;
  top: -7px;
  bottom: 50%;
  width: 1px;
  background: var(--border-divider);
}
.nav-dropdown-item.nav-dropdown-depth-1::after {
  content: '';
  position: absolute;
  left: 13px;
  top: 50%;
  width: 8px;
  height: 1px;
  background: var(--border-divider);
}
.nav-dropdown-item.nav-dropdown-depth-1:hover {
  color: var(--text-strong);
}

.nav-actions {
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.nav-theme {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  margin: -8px 0;
  color: var(--text-muted);
  transition: color var(--t-base);
}
.nav-theme:hover { color: var(--text-base); }
.nav-theme-icon { display: none; }

/* In dark mode, show the sun (click → switch to light) */
:root .nav-theme-sun { display: inline; }
:root .nav-theme-moon { display: none; }

/* In light mode (explicit OR via media), show the moon */
:root[data-theme='light'] .nav-theme-sun { display: none; }
:root[data-theme='light'] .nav-theme-moon { display: inline; }
@media (prefers-color-scheme: light) {
  :root:not([data-theme='dark']) .nav-theme-sun { display: none; }
  :root:not([data-theme='dark']) .nav-theme-moon { display: inline; }
}

.nav-github {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  margin: -8px;
  color: var(--text-muted);
  transition: color var(--t-base);
}
.nav-github:hover { color: var(--text-base); }

.nav-cta-alt {
  background: transparent;
  border: 1px solid var(--border-strong);
  color: var(--text-base);
}
.nav-cta-alt:hover {
  background: var(--surface-2);
  color: var(--text-base);
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  height: 40px;
  padding: 0 18px;
  background: var(--accent-primary);
  color: #fff;
  font-size: var(--fs-sm);
  font-weight: 700;
  letter-spacing: 0.02em;
  border-radius: var(--radius);
  transition: background var(--t-base), border-color var(--t-base), color var(--t-base);
}
.nav-cta:hover {
  background: var(--accent-primary-hover);
  color: #fff;
}
.nav-cta:active {
  transform: translateY(1px);
}
.nav-cta-version {
  font-family: var(--font-mono);
  font-size: var(--fs-2xs);
  font-weight: 500;
  opacity: 0.75;
}

.nav-burger {
  display: none;
  width: 44px;
  height: 44px;
  margin: -8px -10px -8px 0;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 4px;
  color: var(--text-muted);
}
.nav-burger-line {
  display: block;
  width: 20px;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--t-base), opacity var(--t-base);
}
.nav-burger[aria-expanded='true'] .nav-burger-line:nth-child(1) {
  transform: translateY(5.5px) rotate(45deg);
}
.nav-burger[aria-expanded='true'] .nav-burger-line:nth-child(2) {
  opacity: 0;
}
.nav-burger[aria-expanded='true'] .nav-burger-line:nth-child(3) {
  transform: translateY(-5.5px) rotate(-45deg);
}

/* Mobile panel */
.nav-panel {
  display: none;
}
@media (max-width: 720px) {
  .nav-links {
    display: none;
  }
  /* nav-links carried the margin-auto that pushed the actions right; with it
     hidden, right-align the theme + burger toggles explicitly. */
  .nav-actions {
    margin-left: auto;
  }
  .nav-cta-version {
    display: none;
  }
  .nav-burger {
    display: inline-flex;
  }
  .nav-panel {
    display: block;
    position: fixed;
    inset: 64px 0 0 0;
    background: var(--bg-page);
    border-top: 1px solid var(--border-hairline);
    overflow-y: auto;
    overscroll-behavior: contain;
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    transition: transform var(--t-base), opacity var(--t-base), visibility 0s linear var(--t-base);
    z-index: 40;
  }
  .nav-panel.is-open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
    transition: transform var(--t-base), opacity var(--t-base);
  }
  .nav-panel-inner {
    display: flex;
    flex-direction: column;
    padding: 24px;
    gap: 4px;
  }
  .nav-panel-section {
    border-bottom: 1px solid var(--border-hairline);
  }
  .nav-panel-link {
    display: block;
    padding: 16px 8px;
    color: var(--text-base);
    font-size: var(--fs-xl);
    font-weight: 600;
  }
  .nav-panel-section .nav-panel-link {
    border-bottom: none;
  }
  .nav-panel-sublinks {
    display: flex;
    flex-direction: column;
    padding: 0 8px 12px;
    gap: 2px;
  }
  .nav-panel-sublink {
    display: block;
    padding: 8px 14px;
    color: var(--text-muted);
    font-size: var(--fs-base-sm);
    font-weight: 500;
  }
  .nav-panel-sublink:hover { color: var(--text-base); }
  .nav-panel-sublink.nav-panel-sublink-depth-1 {
    padding-left: 28px;
    font-size: var(--fs-sm);
    color: var(--text-tertiary);
  }
  .nav-panel-sublink.nav-panel-sublink-depth-1::before {
    content: '└';
    margin-right: 8px;
    color: var(--text-faint);
  }
  .nav-panel-cta {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    align-self: flex-start;
    margin-top: 16px;
    padding: 12px 20px;
    background: var(--accent-primary);
    color: #fff;
    font-size: var(--fs-base-sm);
    font-weight: 700;
  }
}