/* ─────────────────────────── Top bar ────────────────────────────── */

.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 24px var(--gutter);
  pointer-events: none;
}

.topbar-logo,
.menu-toggle {
  pointer-events: auto;
}

.topbar-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--white);
  transition: color 300ms ease-out;
}

.topbar-logo:hover {
  color: var(--brand-light);
}

.topbar-mark {
  width: 26px;
  height: 26px;
}

.topbar-wordmark {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 20px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

.menu-toggle {
  position: relative;
  z-index: 60;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 7px;
  width: 44px;
  height: 44px;
  align-items: center;
}

.menu-toggle-line {
  display: block;
  width: 28px;
  height: 2px;
  background: var(--white);
  transition: transform 300ms ease-out, background-color 300ms ease-out;
}

.menu-toggle:hover .menu-toggle-line {
  background: var(--brand-light);
}

.menu-open .menu-toggle-line:nth-child(1) {
  transform: translateY(4.5px) rotate(45deg);
}

.menu-open .menu-toggle-line:nth-child(2) {
  transform: translateY(-4.5px) rotate(-45deg);
}

/* ──────────────────────── Menu overlay ──────────────────────────── */

.menu-overlay {
  position: fixed;
  inset: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  background: rgba(10, 10, 10, 0.97);
  opacity: 0;
  visibility: hidden;
  transition: opacity 400ms ease-out, visibility 0s linear 400ms;
}

.menu-open .menu-overlay {
  opacity: 1;
  visibility: visible;
  transition: opacity 400ms ease-out;
}

.menu-list {
  padding: 0 var(--gutter);
  width: 100%;
  max-width: 900px;
  margin: 0 auto;
}

.menu-list a {
  display: flex;
  align-items: baseline;
  gap: 28px;
  padding: 10px 0;
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 500ms var(--ease-out), transform 500ms var(--ease-out);
}

.menu-open .menu-list a {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered entrance for menu items */
.menu-open .menu-list li:nth-child(1) a { transition-delay: 60ms; }
.menu-open .menu-list li:nth-child(2) a { transition-delay: 120ms; }
.menu-open .menu-list li:nth-child(3) a { transition-delay: 180ms; }
.menu-open .menu-list li:nth-child(4) a { transition-delay: 240ms; }
.menu-open .menu-list li:nth-child(5) a { transition-delay: 300ms; }
.menu-open .menu-list li:nth-child(6) a { transition-delay: 360ms; }
.menu-open .menu-list li:nth-child(7) a { transition-delay: 420ms; }

.menu-num {
  font-size: 14px;
  letter-spacing: 0.14em;
  color: var(--brand);
  transition: color 300ms ease-out;
}

.menu-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(36px, 6vw, 72px);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  line-height: 1.15;
  color: var(--white);
  transition: color 300ms ease-out;
}

.menu-list a:hover .menu-name,
.menu-list a:focus-visible .menu-name {
  color: var(--brand-light);
}

.menu-list a:hover .menu-num {
  color: var(--brand-light);
}

/* ───────────────────── Chapter indicator ────────────────────────── */

.chapter-indicator {
  position: fixed;
  top: 50%;
  left: 28px;
  z-index: 30;
  transform: translateY(-50%);
  writing-mode: vertical-rl;
}

.chapter-indicator-item {
  position: absolute;
  top: 0;
  left: 0;
  transform: translateX(-50%) rotate(180deg);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.22em;
  color: var(--muted);
  white-space: nowrap;
  opacity: 0;
  transition: opacity 400ms ease-out;
}

.chapter-indicator-item.active {
  opacity: 1;
}

@media (max-width: 1199px) {
  .chapter-indicator {
    display: none;
  }
}

/* ─────────────────────── Section rhythm ─────────────────────────── */

.chapter {
  position: relative;
  padding: 20vh var(--gutter);
}