/* ============================================================
   Floating pill nav — hide on scroll-down, show on scroll-up
   ============================================================ */

.nav {
  position: fixed;
  top: 18px;
  left: 50%;
  translate: -50% 0;
  z-index: var(--z-nav);
  display: flex;
  padding: 6px;
  border-radius: var(--r-pill);
  background: rgba(18, 18, 18, 0.6);
  border: 1px solid var(--border);
  backdrop-filter: blur(14px) saturate(1.3);
  -webkit-backdrop-filter: blur(14px) saturate(1.3);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
  transition: translate 0.45s var(--ease-out), opacity 0.35s ease;
  will-change: translate;
}

/* hidden (scrolling down) */
.nav.is-hidden {
  translate: -50% -160%;
  opacity: 0;
  pointer-events: none;
}

/* collapsed bar is desktop-hidden; the links are the pill row */
.nav__bar { display: none; }
.nav__links { display: flex; gap: 4px; }

.nav__link {
  position: relative;
  padding: 8px 18px;
  border-radius: var(--r-pill);
  font-size: var(--step--1);
  font-weight: 600;
  color: var(--fg-dim);
  white-space: nowrap;
  transition: color 0.25s ease, background 0.25s ease;
}
.nav__link:hover { color: var(--fg); }

.nav__link.is-active {
  color: #0a0a0a;
  background: var(--accent);
}

/* ============================================================
   Mobile: collapse the pill row behind a hamburger (per
   Old Files/ScrollNav.tsx). The bar shows the active section
   name + a toggle; the links become a dropdown panel anchored
   under the bar at the right edge.
   ============================================================ */
@media (max-width: 768px) {
  /* transparent container — the glass moves to .nav__bar and .nav__links so
     neither is trapped as a descendant of a backdrop-filtered ancestor (which
     would blur the parent's empty backdrop, not the page). */
  .nav {
    left: auto;
    right: 14px;
    top: 14px;
    translate: none;
    display: block;
    padding: 0;
    background: transparent;
    border: none;
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
    box-shadow: none;
  }
  .nav.is-hidden { translate: 0 -160%; }   /* not centred on mobile */

  .nav__bar {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 5px 5px 5px 14px;
    border-radius: var(--r-md);
    background: rgba(18, 18, 18, 0.6);
    border: 1px solid var(--border);
    backdrop-filter: blur(14px) saturate(1.3);
    -webkit-backdrop-filter: blur(14px) saturate(1.3);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
  }
  .nav__current {
    flex: 1 1 auto;
    min-width: 0;
    max-width: 46vw;
    font-size: var(--step--1);
    font-weight: 700;
    letter-spacing: -0.01em;
    color: var(--accent);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  .nav__toggle {
    flex: 0 0 auto;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 38px;
    border-radius: 12px;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--fg);
    cursor: pointer;
    transition: background 0.18s ease, border-color 0.18s ease, color 0.18s ease;
  }
  .nav.is-open .nav__toggle {
    border-color: var(--accent);
    background: rgba(156, 227, 37, 0.14);
    color: var(--accent);
  }

  /* hamburger → X */
  .nav__burger { display: flex; flex-direction: column; gap: 4px; width: 18px; }
  .nav__burger i {
    display: block;
    width: 18px;
    height: 1.8px;
    border-radius: 2px;
    background: currentColor;
    transition: transform 0.22s ease, opacity 0.18s ease;
  }
  .nav.is-open .nav__burger i:nth-child(1) { transform: translateY(5.8px) rotate(45deg); }
  .nav.is-open .nav__burger i:nth-child(2) { opacity: 0; }
  .nav.is-open .nav__burger i:nth-child(3) { transform: translateY(-5.8px) rotate(-45deg); }

  /* dropdown panel */
  .nav__links {
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: 8px;
    min-width: 210px;
    flex-direction: column;
    gap: 4px;
    padding: 8px;
    border-radius: var(--r-md);
    background: rgba(18, 18, 18, 0.6);
    border: 1px solid var(--border);
    backdrop-filter: blur(14px) saturate(1.3);
    -webkit-backdrop-filter: blur(14px) saturate(1.3);
    box-shadow: 0 18px 40px -16px rgba(0, 0, 0, 0.7), inset 0 1px 0 rgba(255, 255, 255, 0.07);
    transform-origin: top right;
    opacity: 0;
    transform: translateY(-8px) scale(0.98);
    pointer-events: none;
    transition: opacity 0.2s var(--ease-out), transform 0.2s var(--ease-out);
  }
  .nav.is-open .nav__links {
    opacity: 1;
    transform: none;
    pointer-events: auto;
  }

  .nav__link {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 12px 14px;
    border-radius: 12px;
    border: 1px solid transparent;
    font-size: var(--step-0);
    color: var(--fg-dim);
    white-space: normal;
    text-align: center;
  }
  .nav__link.is-active {
    color: var(--accent);
    background: rgba(156, 227, 37, 0.12);
    border-color: var(--accent);
  }
}