/* ============================================================
   SIGNATURE NAVIGATION — "the film strip"
   The nav is a length of 35mm film: perforated rails top and
   bottom, each link a frame. On hover a frame does a staggered
   per-letter "advance" flip to projector gold while a beam of
   light sweeps across it. A playhead glides along the bottom
   rail to the section you're viewing.
   ============================================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(14, 17, 22, 0.72);
  backdrop-filter: blur(14px) saturate(1.2);
  -webkit-backdrop-filter: blur(14px) saturate(1.2);
  border-bottom: 1px solid var(--line);
}

.filmstrip-nav {
  position: relative;
  max-width: var(--maxw);
  margin: 0 auto;
  height: 76px;
  padding: 0 var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

/* --- Perforated sprocket rails (top + bottom of the strip) --- */
.filmstrip-nav::before,
.filmstrip-nav::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 6px;
  background-image: repeating-linear-gradient(
    90deg,
    rgba(236, 231, 222, 0.16) 0 9px,
    transparent 9px 26px
  );
  background-size: 26px 6px;
  pointer-events: none;
}
.filmstrip-nav::before { top: 0; }
.filmstrip-nav::after  { bottom: 0; }

/* Film "advances" — perforations scroll — while you interact */
@media (prefers-reduced-motion: no-preference) {
  .filmstrip-nav:hover::before,
  .filmstrip-nav:hover::after,
  .filmstrip-nav:focus-within::before,
  .filmstrip-nav:focus-within::after {
    animation: perf-advance 0.9s linear infinite;
  }
}
@keyframes perf-advance {
  to { background-position: 26px 0; }
}

/* --- Brand monogram --- */
.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 0.25rem;
  font-family: var(--mono);
  letter-spacing: 0.05em;
}
.brand__mark {
  font-size: 1.15rem;
  font-weight: 500;
  color: var(--paper);
}
.brand__rx {
  font-size: 0.7rem;
  color: var(--gold);
  transform: translateY(-0.4em);
  transition: transform 0.4s var(--ease);
}
.brand:hover .brand__rx { transform: translateY(-0.4em) rotate(-8deg); }

/* --- Link list --- */
.nav-links {
  display: flex;
  align-items: center;
  gap: clamp(0.5rem, 2vw, 1.75rem);
}

.frame__link {
  position: relative;
  display: inline-block;
  padding: 0.5rem 0.65rem;
  overflow: hidden;
  font-weight: 500;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  color: var(--paper);
  isolation: isolate;
}

/* Projector-light beam sweeping across the frame on hover */
.frame__link::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: linear-gradient(
    105deg,
    transparent 38%,
    rgba(227, 172, 85, 0.22) 50%,
    transparent 62%
  );
  transform: translateX(-130%);
  transition: transform 0.65s var(--ease);
  pointer-events: none;
}
.frame__link:hover::after,
.frame__link:focus-visible::after { transform: translateX(130%); }

/* --- Per-letter "frame advance" flip (built by main.js) --- */
.frame__flip { display: inline-flex; }

.frame__char {
  position: relative;
  display: inline-block;
  height: 1em;
  line-height: 1;
  overflow: hidden;
  vertical-align: bottom;
}
.frame__space { display: inline-block; width: 0.32em; }

.frame__face {
  display: block;
  height: 1em;
  transition: transform 0.42s var(--ease);
  transition-delay: calc(var(--i, 0) * 26ms);
}
.frame__face--bot { color: var(--gold); }

/* On hover/focus: both faces slide up one frame → gold reveals */
.frame__link:hover .frame__face,
.frame__link:focus-visible .frame__face {
  transform: translateY(-100%);
}

/* Fallback before JS enhances the label */
.frame__label { display: inline-block; }

/* Active section: keep the frame lit in gold */
.frame--active .frame__face { transform: translateY(-100%); }
.frame--active .frame__link { color: var(--gold); }

/* --- Playhead gliding along the bottom rail --- */
.playhead {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gold);
  box-shadow: 0 0 12px rgba(227, 172, 85, 0.6);
  transition: transform 0.5s var(--ease), width 0.5s var(--ease), opacity 0.3s var(--ease);
  opacity: 0;
  pointer-events: none;
}
.playhead.is-visible { opacity: 1; }
.playhead::before {
  content: "";
  position: absolute;
  top: -6px;
  left: 50%;
  transform: translateX(-50%);
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  border-top: 6px solid var(--gold);
}

/* --- Mobile toggle (hidden on desktop) --- */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 0.6rem;
  z-index: 2;
}
.nav-toggle__bar {
  width: 26px;
  height: 2px;
  background: var(--paper);
  transition: transform 0.35s var(--ease), opacity 0.35s var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) { transform: translateY(-0px) rotate(-45deg); }

/* ============================================================
   MOBILE
   ============================================================ */
@media (max-width: 760px) {
  .nav-toggle { display: flex; }
  .playhead { display: none; }

  .nav-links {
    position: absolute;
    top: 76px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    background: rgba(14, 17, 22, 0.97);
    backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--line);
    padding: 0.5rem var(--gutter) 1.5rem;
    clip-path: inset(0 0 100% 0);
    transition: clip-path 0.45s var(--ease);
  }
  .nav-links.is-open { clip-path: inset(0 0 0 0); }

  .frame { width: 100%; border-bottom: 1px solid var(--line); }
  .frame:last-child { border-bottom: 0; }
  .frame__link {
    display: block;
    width: 100%;
    padding: 1.1rem 0.25rem;
    font-size: 1.35rem;
    font-family: var(--serif);
    letter-spacing: 0;
  }
}