/* ================================================================
   NAVIGATION — ナビゲーションバー、ハンバーガー、モバイルメニュー
   ================================================================ */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 28px var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: background 0.4s, padding 0.4s;
  background: #fff;
  border-bottom: 1px solid #e0e0e0;
}
nav.scrolled {
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(16px);
  padding: 18px var(--gutter);
  border-bottom: 1px solid #e0e0e0;
}

/* ---- LOGO ---- */
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: clamp(20px, 2.2vw, 28px);
  font-weight: 300;
  letter-spacing: 0.12em;
  cursor: pointer;
  position: relative;
  color: #000;
}
.nav-logo span { color: var(--color-accent); }

/* ---- LINKS ---- */
.nav-links {
  display: flex;
  gap: clamp(24px, 4vw, 56px);
  list-style: none;
}
.nav-links a {
  font-size: 13px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: #666;
  transition: color 0.3s;
}
.nav-links a:hover { color: #000; }

/* ---- CTA ---- */
.nav-cta {
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  border: 1px solid var(--color-accent);
  color: var(--color-accent);
  padding: 10px 28px;
  transition: background 0.3s, color 0.3s;
}
.nav-cta:hover { background: var(--color-accent); color: var(--color-bg); }

/* ---- HAMBURGER ---- */
.hamburger {
  display: none;
  width: 44px; height: 44px;
  cursor: pointer;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  flex-direction: column;
  gap: 6px;
}
.hamburger span {
  display: block;
  width: 26px; height: 1.5px;
  background: #000;
  transition: transform 0.35s cubic-bezier(0.77,0,0.18,1), opacity 0.25s ease, width 0.3s ease;
}
.hamburger:hover span { opacity: 0.6; }
.hamburger.active span:nth-child(1) { transform: translateY(7.5px) rotate(45deg); }
.hamburger.active span:nth-child(2) { opacity: 0; width: 0; }
.hamburger.active span:nth-child(3) { transform: translateY(-7.5px) rotate(-45deg); }

/* ---- MOBILE MENU ---- */
.mobile-menu {
  position: fixed;
  inset: 0;
  background: #fff;
  z-index: 99;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 32px;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.4s ease, visibility 0.4s ease;
}
.mobile-menu.open { opacity: 1; visibility: visible; }
.mobile-menu a {
  font-family: var(--font-display);
  font-size: clamp(32px, 6vw, 56px);
  font-weight: 300;
  letter-spacing: 0.04em;
  opacity: 0;
  transform: translateY(16px);
  transition: color 0.3s, opacity 0.4s ease, transform 0.4s ease;
  color: #000;
}
.mobile-menu.open a:nth-child(1) { opacity: 1; transform: none; transition-delay: 0.10s; }
.mobile-menu.open a:nth-child(2) { opacity: 1; transform: none; transition-delay: 0.18s; }
.mobile-menu.open a:nth-child(3) { opacity: 1; transform: none; transition-delay: 0.26s; }
.mobile-menu.open a:nth-child(4) { opacity: 1; transform: none; transition-delay: 0.34s; }
.mobile-menu.open a:nth-child(5) { opacity: 1; transform: none; transition-delay: 0.42s; }
.mobile-menu a:hover { color: var(--color-accent); }

/* ---- RESPONSIVE ---- */
@media (max-width: 768px) {
  .nav-links, .nav-cta { display: none; }
  .hamburger { display: flex; }
}