/* ═══════════════════════════════════════════════════
   NAV — 多層樹狀導覽（桌機 mega menu / 手機全螢幕）
   前衛東方官網
   ═══════════════════════════════════════════════════ */

/* ── Base ── */
.site-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 48px;
  background: transparent;
  color: var(--card);
  transition:
    background var(--duration-normal) var(--ease-out),
    color var(--duration-normal) var(--ease-out),
    padding var(--duration-normal) var(--ease-out),
    box-shadow var(--duration-normal) var(--ease-out);
}

.site-nav.scrolled {
  background: rgba(247, 245, 241, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  color: var(--ink);
  padding: 14px 48px;
  box-shadow: 0 2px 20px rgba(28, 27, 24, 0.08);
}

/* ── Logo ── */
.nav-logo {
  display: flex;
  flex-direction: column;
  line-height: 1;
  text-decoration: none;
  color: inherit;
  gap: 2px;
}
.nav-logo .logo-en {
  font-family: 'Cormorant Garamond', Georgia, serif;
  font-size: 1.2rem;
  font-weight: 500;
  letter-spacing: 0.15em;
  color: inherit;
}
.nav-logo .logo-zh {
  font-family: 'Noto Serif TC', 'Noto Sans TC', serif;
  font-size: 0.6rem;
  font-weight: 300;
  letter-spacing: 0.25em;
  color: inherit;
  opacity: 0.75;
}

/* ═══════════════════════════════════════════
   DESKTOP NAV （> 960px）
═══════════════════════════════════════════ */
.nav-menu {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-item {
  position: relative;
}

.nav-top-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-family: 'Noto Sans TC', sans-serif;
  font-size: 0.88rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  text-decoration: none;
  color: inherit;
  padding: 6px 0;
  position: relative;
  transition: color var(--duration-fast) var(--ease-out);
}

.nav-top-link::after {
  content: '';
  position: absolute;
  left: 0; bottom: -2px;
  width: 0; height: 1px;
  background: currentColor;
  transition: width var(--duration-normal) var(--ease-out);
}
.nav-top-link:hover::after,
.nav-top-link:focus-visible::after { width: 100%; }
.nav-top-link:hover { color: var(--accent); }

.nav-caret {
  font-size: 0.68em;
  opacity: 0.75;
  transition: transform var(--duration-fast) var(--ease-out);
}
.nav-item.has-children:hover .nav-caret,
.nav-item.hover .nav-caret {
  transform: rotate(-180deg);
}

/* ── Mega Menu（桌機 hover 彈出）── */
.nav-mega {
  position: absolute;
  top: calc(100% + 12px);
  left: 50%;
  transform: translate(-50%, -6px);
  min-width: 240px;
  background: rgba(247, 245, 241, 0.98);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  color: var(--ink);
  border: 1px solid rgba(181, 149, 96, 0.18);
  border-radius: 6px;
  box-shadow: 0 16px 48px rgba(28, 27, 24, 0.18);
  padding: 20px 24px;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition:
    opacity 150ms var(--ease-out),
    transform 180ms var(--ease-out),
    visibility 0s linear 150ms;
  z-index: 120;
}

/* 左邊懸崖避免蓋到 logo */
.nav-item:first-child .nav-mega { left: 0; transform: translate(0, -6px); }
.nav-item:last-child .nav-mega  { left: auto; right: 0; transform: translate(0, -6px); }

.nav-item.has-children:hover > .nav-mega,
.nav-item.hover > .nav-mega,
.nav-item.has-children:focus-within > .nav-mega {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translate(-50%, 0);
  transition:
    opacity 180ms var(--ease-out),
    transform 220ms var(--ease-out),
    visibility 0s linear 0s;
}
.nav-item:first-child.has-children:hover > .nav-mega,
.nav-item:first-child.hover > .nav-mega { transform: translate(0, 0); }
.nav-item:last-child.has-children:hover > .nav-mega,
.nav-item:last-child.hover > .nav-mega { transform: translate(0, 0); }

/* mega inner: 自動分欄 */
.nav-mega-inner {
  display: grid;
  gap: 28px 36px;
}
.nav-mega--narrow .nav-mega-inner { grid-template-columns: 1fr; min-width: 220px; }
.nav-mega--mid    .nav-mega-inner { grid-template-columns: repeat(2, minmax(180px, 1fr)); min-width: 460px; }
.nav-mega--wide   .nav-mega-inner { grid-template-columns: repeat(3, minmax(180px, 1fr)); min-width: 620px; }

.nav-mega-col { min-width: 0; }

.nav-submenu-title {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: 'Noto Serif TC', 'Noto Sans TC', serif;
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
  letter-spacing: 0.05em;
  padding-bottom: 8px;
  margin-bottom: 10px;
  border-bottom: 1px solid rgba(181, 149, 96, 0.24);
  width: 100%;
}
.nav-submenu-title:hover { color: var(--accent-dark, #8a6f46); }
.nav-submenu-title .nav-arrow { font-size: 0.7em; opacity: 0.7; }

.nav-submenu-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.nav-grandchild a {
  display: block;
  font-family: 'Noto Sans TC', sans-serif;
  font-size: 0.82rem;
  font-weight: 400;
  color: var(--ink);
  text-decoration: none;
  padding: 4px 0;
  letter-spacing: 0.04em;
  transition: color var(--duration-fast) var(--ease-out), padding-left var(--duration-fast) var(--ease-out);
}
.nav-grandchild a:hover {
  color: var(--accent);
  padding-left: 6px;
}

/* ── CTA Button ── */
.nav-cta {
  font-family: 'Noto Sans TC', sans-serif;
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-decoration: none;
  color: var(--card);
  background: var(--accent);
  padding: 10px 24px;
  border-radius: var(--radius-sm);
  transition:
    background var(--duration-fast) var(--ease-out),
    transform var(--duration-fast) var(--ease-out);
  white-space: nowrap;
}
.nav-cta:hover { background: var(--accent-light); transform: translateY(-1px); }
.nav-cta:active { transform: translateY(0); background: var(--accent-dark); }

/* ── Hamburger ── */
.nav-hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 36px;
  height: 36px;
  padding: 6px;
  background: transparent;
  border: none;
  cursor: pointer;
  z-index: 110;
  color: inherit;
}
.nav-hamburger span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: currentColor;
  border-radius: 2px;
  transform-origin: center;
  transition:
    transform var(--duration-normal) var(--ease-out),
    opacity var(--duration-fast) var(--ease-out),
    width var(--duration-normal) var(--ease-out);
}
.nav-hamburger[aria-expanded="true"] span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.nav-hamburger[aria-expanded="true"] span:nth-child(2) { opacity: 0; width: 0; }
.nav-hamburger[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* ── Mobile overlay ── */
.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 90;
  background: var(--dark);
  opacity: 0;
  transition: opacity var(--duration-normal) var(--ease-out);
  pointer-events: none;
}
.nav-overlay.open {
  pointer-events: auto;
  opacity: 0.97;
}

/* ═══════════════════════════════════════════
   MOBILE NAV  （≤ 960px）
═══════════════════════════════════════════ */
@media (max-width: 960px) {
  .site-nav { padding: 18px 24px; }
  .site-nav.scrolled { padding: 14px 24px; }

  .nav-hamburger { display: flex; }
  .nav-overlay { display: block; }

  /* 全螢幕側邊 panel */
  .nav-menu {
    position: fixed;
    top: 0; right: 0; bottom: 0;
    width: min(360px, 88vw);
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--dark);
    padding: 92px 32px 60px;
    z-index: 105;
    transform: translateX(100%);
    transition: transform var(--duration-normal) var(--ease-out);
    overflow-y: auto;
    pointer-events: none;
  }
  .nav-menu.open {
    transform: translateX(0);
    pointer-events: auto;
  }

  .nav-item {
    width: 100%;
    border-bottom: 1px solid rgba(200, 191, 176, 0.12);
  }
  .nav-item:last-child { border-bottom: none; }

  .nav-top-link {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    padding: 16px 0;
    font-size: 1rem;
    letter-spacing: 0.1em;
    color: var(--bg);
  }
  .nav-top-link::after { display: none; }
  .nav-top-link:hover { color: var(--accent); }

  .nav-caret {
    font-size: 0.85em;
    opacity: 0.75;
    transition: transform var(--duration-normal) var(--ease-out);
  }
  .nav-item.expanded > .nav-top-link .nav-caret { transform: rotate(-180deg); }

  /* Mobile 版 mega：變成摺疊樹 */
  .nav-mega {
    position: static;
    transform: none;
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    background: transparent;
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
    border: none;
    border-radius: 0;
    box-shadow: none;
    padding: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height 280ms var(--ease-out);
  }
  .nav-item.expanded > .nav-mega {
    max-height: 2000px;
    padding: 4px 0 14px;
  }

  .nav-mega-inner {
    display: block;
  }
  .nav-mega--narrow .nav-mega-inner,
  .nav-mega--mid .nav-mega-inner,
  .nav-mega--wide .nav-mega-inner {
    grid-template-columns: 1fr;
    min-width: 0;
  }

  .nav-mega-col {
    padding: 4px 0 0 14px;
    border-left: 1px solid rgba(181, 149, 96, 0.25);
    margin-bottom: 10px;
  }

  .nav-submenu-title {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    font-size: 0.92rem;
    color: var(--accent);
    padding: 10px 0;
    margin-bottom: 0;
    border-bottom: none;
  }
  .nav-submenu-title .nav-arrow {
    transition: transform var(--duration-normal) var(--ease-out);
  }
  .nav-mega-col.expanded > .nav-submenu-title .nav-arrow {
    transform: rotate(-180deg);
  }

  .nav-submenu-list {
    max-height: 0;
    overflow: hidden;
    transition: max-height 260ms var(--ease-out);
  }
  .nav-mega-col.expanded .nav-submenu-list {
    max-height: 1200px;
    padding: 2px 0 6px;
  }
  /* 沒子子項的欄位，清單永遠顯示（雖然是空的） */
  .nav-mega-col:not(.has-children) .nav-submenu-list {
    max-height: none;
  }

  .nav-grandchild a {
    color: rgba(247, 245, 241, 0.78);
    padding: 8px 0 8px 12px;
    font-size: 0.86rem;
  }
  .nav-grandchild a:hover {
    color: var(--accent);
    padding-left: 16px;
  }

  /* 桌機版 CTA 藏起來（LINE 按鈕） */
  .nav-cta { display: none; }
}