/* ============================================================
   SHARED SITE NAV — single source of truth for every page.
   Link this AFTER each page's own <style> (or reset) so its
   design tokens (--space-lg, --border-subtle, --accent, ...) resolve.
   Chapter-only reading tabs (.tab-bar / .nav-tabs-inline) and the
   scroll-collapse trigger stay in the chapter pages themselves; this
   file only owns the nav shell and drives the kebab via body.nav-collapsed.
   ============================================================ */

.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  /* transparent at the top (the hero flows up behind it); frosts in on scroll */
  background: transparent;
  border-bottom: 1px solid transparent;
  height: var(--nav-height, 64px);
  transition: background 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease, backdrop-filter 0.3s ease;
}
.nav.scrolled {
  background: rgba(10, 26, 40, 0.55);
  backdrop-filter: blur(16px) saturate(160%);
  -webkit-backdrop-filter: blur(16px) saturate(160%);
  border-bottom: 1px solid var(--border-subtle);
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.18);
}
.nav.scrolled { box-shadow: 0 1px 32px rgba(0,0,0,0.3); }

.nav-inner {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  position: relative;
}

/* Brand — wordmark by default, brain/bolt icon at very narrow widths */
.nav-brand {
  display: inline-flex;
  align-items: center;
  font-family: 'Montserrat', sans-serif;
  font-size: 15px;
  font-weight: 300;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: var(--text-secondary);
}
.nav-brand strong { font-weight: 800; color: var(--text-primary); }
.nav-brand-icon { display: none; width: 30px; height: 30px; object-fit: contain; }

/* Inline links */
.nav-links { display: flex; gap: var(--space-lg); align-items: center; transition: opacity 0.35s ease 0.1s; }
.nav-link { font-size: var(--text-sm); font-weight: 400; color: var(--text-secondary); transition: color 0.2s; }
.nav-link:hover { color: var(--text-primary); }
.nav-link.active { color: var(--accent); }

/* Chapters hover dropdown (wide screens) */
.chap-drop-wrap { position: relative; }
.chap-drop-caret { margin-left: 3px; vertical-align: middle; opacity: 0.5; transition: transform 0.2s, opacity 0.2s; }
.chap-drop-wrap:hover .chap-drop-caret { transform: rotate(180deg); opacity: 1; }
.chap-drop { display: none; position: absolute; top: 100%; left: 50%; transform: translateX(-50%); padding-top: 12px; z-index: 9000; }
.chap-drop-wrap:hover .chap-drop { display: block; }
.chap-drop::before { content: ''; position: absolute; top: 0; left: 0; right: 0; height: 12px; }
.chap-drop-inner { background: rgba(12, 28, 42, 0.98); backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px); border: 1px solid rgba(255,255,255,0.10); border-radius: 10px; padding: 6px; min-width: 220px; box-shadow: 0 12px 40px rgba(0,0,0,0.5); display: flex; flex-direction: column; }
.chap-drop-item { display: flex; align-items: center; gap: 10px; padding: 8px 14px; border-radius: 6px; font-family: 'Montserrat', sans-serif; font-size: 13px; font-weight: 500; color: rgba(255,255,255,0.75); transition: all 0.15s; white-space: nowrap; }
.chap-drop-item:hover { background: rgba(255,255,255,0.07); color: #ffffff; }
.chap-drop-item.current { color: var(--accent); }
.chap-drop-num { font-size: 11px; font-weight: 700; color: var(--card-accent); opacity: 0.6; min-width: 18px; }

/* Kebab menu button + dropdown — appears on narrow width OR chapter scroll-collapse */
.nav-menu-wrap {
  position: absolute;
  right: var(--space-lg);
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  align-items: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s ease 0.1s;
}
.nav-menu-btn { background: none; border: 1px solid var(--border-subtle); border-radius: var(--radius-sm); width: 36px; height: 36px; display: flex; align-items: center; justify-content: center; cursor: pointer; color: var(--text-secondary); transition: all 0.2s; }
.nav-menu-btn:hover { color: var(--text-primary); border-color: var(--border-medium); background: var(--surface-raised); }
.nav-menu-dropdown { display: none; position: absolute; top: calc(100% + 12px); right: 0; background: rgba(12, 28, 42, 0.98); backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px); border: 1px solid var(--border-medium); border-radius: var(--radius-md); padding: 6px; min-width: 190px; box-shadow: 0 8px 32px rgba(0,0,0,0.5); }
.nav-menu-dropdown.open { display: flex; flex-direction: column; }
.nav-menu-item { font-size: var(--text-sm); font-weight: 500; color: var(--text-secondary); padding: 10px 16px; border-radius: 6px; transition: all 0.15s; }
.nav-menu-item:hover { color: var(--text-primary); background: rgba(255,255,255,0.05); }

/* Kebab's collapsible Chapters submenu */
.nav-menu-sub { display: none; flex-direction: column; padding: 4px 0 2px; }
.nav-menu-sub.open { display: flex; }
.nav-menu-sub-toggle { display: flex; align-items: center; justify-content: space-between; cursor: pointer; }
.nav-menu-sub-toggle .nav-menu-sub-caret { transition: transform 0.2s; margin-left: auto; opacity: 0.5; }
.nav-menu-sub-toggle.open .nav-menu-sub-caret { transform: rotate(180deg); opacity: 1; }
.nav-menu-sub .chap-drop-item { padding: 6px 12px; font-size: 12px; border-radius: 5px; }
.nav-menu-sub .chap-drop-num { font-size: 10px; }

/* Chapter scroll-collapse hooks — inert unless the chapter JS sets body.nav-collapsed */
body.nav-collapsed .nav-links { opacity: 0; pointer-events: none; }
body.nav-collapsed .nav-menu-wrap { opacity: 1; pointer-events: auto; transition-delay: 0s; }

/* Width-responsive collapse (every page) */
@media (max-width: 600px) {
  .nav-links { display: none; }
  .nav-menu-wrap { opacity: 1; pointer-events: auto; }
  /* wordmark → compact icon, freeing room for the inline reading tabs + menu */
  .nav-brand-text { display: none; }
  .nav-brand-icon { display: block; }
}

.nav-menu-sub-toggle:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }