.tools-nav-back {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  margin-right: .55rem;
  border: 1px solid var(--clr-border);
  border-radius: 8px;
  background: var(--clr-surface);
  color: var(--clr-muted);
  text-decoration: none;
  font-size: 0;
  line-height: 1;
  box-shadow: var(--shadow-sm);
  transition: border-color .15s, color .15s, background .15s, transform .15s;
}

.tools-nav-back:hover {
  color: var(--clr-text);
  border-color: var(--clr-primary);
  background: color-mix(in oklab, var(--clr-surface) 86%, var(--clr-primary));
  transform: translateX(-1px);
}

.tools-nav-back svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  stroke-width: 2.2;
  fill: none;
}

.tools-nav-back:focus-visible,
.hamburger-btn:focus-visible,
.nav-menu a:focus-visible {
  outline: none;
  box-shadow: 0 0 0 2px var(--clr-ui-focus-ring);
}

.tools-nav-title-row {
  display: flex;
  align-items: center;
  min-width: 0;
}

/* Reserve room for floating language + menu controls on narrow headers. */
.header-inner > div:first-child {
  padding-top: .35rem;
}

.tools-nav-floating-controls {
  position: fixed;
  top: 1rem;
  right: 1rem;
  z-index: 1400;
  display: inline-flex;
  align-items: center;
  gap: .5rem;
}

.tools-nav-floating-controls .lang-switcher {
  order: 2;
  flex: 0 0 98px;
  width: 98px;
  margin: 0;
}

.tools-nav-floating-controls .theme-toggle {
  order: 1;
  flex: 0 0 auto;
  width: 98px;
  margin: 0;
  border: 1px solid var(--clr-ui-border-soft);
  background: var(--clr-ui-track);
  box-shadow: none;
}

.tools-nav-floating-controls .tools-nav-theme-float {
  max-width: 0;
  opacity: 0;
  transform: translateX(10px);
  overflow: hidden;
  pointer-events: none;
  transition: max-width .26s ease, opacity .18s ease, transform .26s ease;
}

.tools-nav-floating-controls.menu-open .tools-nav-theme-float {
  max-width: 98px;
  opacity: 1;
  transform: translateX(0);
  pointer-events: auto;
}

.tools-nav-floating-controls .theme-toggle:hover {
  border-color: var(--clr-primary);
}

body.dark .tools-nav-floating-controls .theme-toggle {
  border-color: var(--clr-ui-border-soft);
  background: var(--clr-ui-track);
  box-shadow: none;
}

.tools-nav-floating-controls .hamburger-btn {
  order: 3;
}

.hamburger-btn {
  position: relative;
  z-index: 1;
  width: 40px;
  height: 40px;
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius, 8px);
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  padding: 8px;
  transition: all 0.3s;
  opacity: 0.6;
}

.hamburger-btn:hover {
  opacity: 1;
  border-color: var(--clr-primary);
}

.hamburger-btn span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--clr-text);
  border-radius: 1px;
  transition: all 0.3s;
}

.hamburger-btn.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.hamburger-btn.open span:nth-child(2) {
  opacity: 0;
}

.hamburger-btn.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

.nav-menu {
  position: fixed;
  top: 0;
  right: -320px;
  width: 320px;
  height: 100vh;
  background: var(--clr-surface);
  border-left: 1px solid var(--clr-border);
  z-index: 1300;
  display: flex;
  flex-direction: column;
  padding: 5rem 1.1rem 1.4rem;
  gap: 0.85rem;
  transition: right 0.3s ease;
  box-shadow: var(--shadow-side);
  overflow-y: auto;
}

.nav-menu.open {
  right: 0;
}

.nav-menu a {
  color: var(--clr-muted);
  font-family: var(--font-mono, 'JetBrains Mono', 'Fira Code', monospace);
  font-size: var(--txt-md-plus);
  padding: 0.6rem 0.8rem;
  border-radius: var(--radius, 8px);
  border-left: 2px solid transparent;
  transition: all 0.15s;
  text-decoration: none;
}

.nav-menu a:hover {
  color: var(--clr-text);
  background: color-mix(in oklab, var(--clr-surface) 85%, var(--clr-primary));
  border-left-color: var(--clr-primary);
}

.nav-menu a.active {
  color: var(--clr-primary);
  background: color-mix(in oklab, var(--clr-surface) 82%, var(--clr-primary));
  border-left: 2px solid var(--clr-primary);
}

.nav-menu-group {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.nav-menu-group-title {
  margin: 0.35rem 0 0.2rem;
  padding: 0 0.35rem;
  font-family: var(--font-mono, 'JetBrains Mono', 'Fira Code', monospace);
  font-size: var(--txt-sm);
  font-weight: var(--txt-w-bold);
  letter-spacing: var(--txt-tracking-wide);
  text-transform: uppercase;
  color: var(--clr-muted);
}

.nav-menu-item {
  display: block;
}

.nav-menu-group--untitled .nav-menu-item {
  padding-left: 0.35rem;
}

.nav-menu-item-indented {
  margin-left: 0;
}

.nav-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--clr-overlay-soft);
  z-index: 1200;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s;
}

.nav-overlay.open {
  opacity: 1;
  visibility: visible;
}

@media (max-width: 780px) {
  .header-inner > div:first-child {
    padding-right: 3rem;
  }

  .nav-menu {
    width: min(320px, 92vw);
  }

  .tools-nav-floating-controls {
    top: .85rem;
    right: .85rem;
  }

  .tools-nav-back {
    width: 32px;
    height: 32px;
    margin-right: .45rem;
  }
}