/* ==========================================
   LENS. — Navigation
   ========================================== */

.site-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 28px var(--pad-x);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* backdrop-filter を ::before に移動
   nav 自体に適用すると position:fixed の子要素(nav-links)の
   基準座標が崩れるため */
.site-nav::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(248, 248, 248, 0.92);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  opacity: 0;
  transition: opacity 0.5s ease;
  z-index: -1;
}

.site-nav.scrolled::before {
  opacity: 1;
}

/* ---- Logo ---- */
.nav-logo {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 500;
  letter-spacing: 0.18em;
  color: var(--text-primary);
  transition: opacity 0.3s ease;
}
.nav-logo:hover { opacity: 0.45; }

/* ---- Links ---- */
.nav-links {
  display: flex;
  align-items: center;
  gap: clamp(28px, 4vw, 52px);
  list-style: none;
}

.nav-links a {
  font-family: var(--font-label);
  font-size: 11px;
  font-weight: 400;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-primary);
  position: relative;
  transition: opacity 0.3s ease;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px; left: 0;
  width: 0; height: 1px;
  background: var(--text-primary);
  transition: width 0.4s ease;
}

.nav-links a:hover { opacity: 0.45; }
.nav-links a:hover::after { width: 100%; }

/* ---- Mobile Toggle ---- */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  background: none;
  border: none;
  padding: 4px;
  z-index: 101;
}
.nav-toggle span {
  display: block;
  width: 22px; height: 1px;
  background: var(--text-primary);
  transition: transform 0.4s ease, opacity 0.4s ease;
}
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---- Mobile Overlay ---- */
.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(26, 26, 26, 0.15);
  z-index: 99;
}
.nav-overlay.open { display: block; }

/* ---- Mobile ---- */
@media (max-width: 767px) {
  .nav-toggle { display: flex; }

  .nav-links {
    position: fixed;
    top: 0; right: 0; bottom: 0;
    width: 64vw; max-width: 260px;
    background: var(--white);
    flex-direction: column;
    justify-content: center;
    align-items: flex-start;
    padding: 80px 44px;
    gap: 32px;
    transform: translateX(100%);
    transition: transform 0.5s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    z-index: 100;
  }
  .nav-links.open { transform: translateX(0); }

  .nav-links a {
    font-size: 12px;
    letter-spacing: 0.38em;
  }
}