/* ===============================================================
   nav.css — 顶部导航栏 (美术馆 / 策展风格)
   =============================================================== */

/* ── 导航 CSS 变量 ── */
:root {
  --nav-height: 60px;
  --nav-bg: rgba(28, 20, 15, 0.92);
  --nav-text: #d4c5a9;
  --nav-text-hover: #c9a96e;
  --nav-underline: var(--gold);
  --nav-shadow: 0 1px 0 rgba(168, 133, 61, 0.08);
  --nav-shadow-scrolled: 0 1px 0 rgba(168, 133, 61, 0.18), 0 4px 24px rgba(0, 0, 0, 0.25);
  --nav-mobile-bg: rgba(23, 19, 12, 0.98);
  --nav-overlay-bg: rgba(0, 0, 0, 0.45);
  --nav-divider: 1px solid rgba(168, 133, 61, 0.1);
}

/* ── 顶部导航容器 ── */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-height);
  border-bottom: 1px solid transparent;
  transition:
    border-color var(--duration-base) var(--ease-out),
    box-shadow var(--duration-base) var(--ease-out);
}

/* Glass 毛玻璃效果通过伪元素实现，避免创建 fixed 子元素的限制容器 */
.nav::before {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(16px);
  -webkit-backdrop-filter: saturate(180%) blur(16px);
  transition: background var(--duration-base) var(--ease-out);
}

/* 滚动后显影 */
.nav[data-scrolled="true"] {
  border-bottom-color: rgba(168, 133, 61, 0.15);
  box-shadow: var(--nav-shadow-scrolled);
}

/* ── 内部三栏布局 ── */
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ── 左侧: Logo ── */
.nav__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--nav-text);
  letter-spacing: 0.08em;
  transition: color var(--duration-fast);
  flex-shrink: 0;
  text-decoration: none;
}

.nav__logo:hover {
  color: var(--nav-text-hover);
}

/* 金色装饰元素 */
.nav__logo-decor {
  display: block;
  width: 8px;
  height: 8px;
  background: var(--gold);
  transform: rotate(45deg);
  flex-shrink: 0;
  opacity: 0.7;
  transition: opacity var(--duration-fast), transform var(--duration-base);
}

.nav__logo:hover .nav__logo-decor {
  opacity: 1;
  transform: rotate(135deg);
}

/* ── 中间: 导航链接 (桌面端) ── */
.nav__menu {
  display: flex;
  align-items: center;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: clamp(1.5rem, 4vw, 2.8rem);
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav__link {
  position: relative;
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--nav-text);
  padding: 0.25em 0;
  text-decoration: none;
  transition: color var(--duration-base) var(--ease-out);
  cursor: pointer;
}

.nav__link:hover {
  color: var(--nav-text-hover);
}

/* 底部下划线: 默认隐藏，从中间展开 */
.nav__link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--nav-underline);
  transition:
    width var(--duration-base) var(--ease-out),
    left var(--duration-base) var(--ease-out);
}

.nav__link:hover::after {
  left: 0;
  width: 100%;
}

/* Active 状态 */
.nav__link--active {
  color: var(--nav-text-hover);
}

.nav__link--active::after {
  left: 0;
  width: 100%;
}

/* ── 右侧: 操作按钮组 ── */
.nav__actions {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex-shrink: 0;
}

/* ═══════════════════════════════════════════
   桌面端 (>1024px): 水平导航
   ═══════════════════════════════════════════ */

@media (min-width: 1024px) {
  .nav__hamburger {
    display: none;
  }
}


/* ═══════════════════════════════════════════
   移动端 (≤1023px): 汉堡菜单 + 滑入面板
   ═══════════════════════════════════════════ */

@media (max-width: 1023px) {
  /* 隐藏桌面端菜单，改为固定定位面板 */
  .nav__menu {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--nav-mobile-bg);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: var(--nav-divider);
    padding: var(--space-md) 0;
    opacity: 0;
    pointer-events: none;
    transform: translateY(-8px);
    transition:
      opacity var(--duration-base) var(--ease-out),
      transform var(--duration-base) var(--ease-out);
  }

  .nav__menu--open {
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
  }

  /* 纵向链接列表 */
  .nav__links {
    flex-direction: column;
    gap: 0;
    padding: 0 var(--space-lg);
  }

  .nav__link {
    display: block;
    font-size: 0.95rem;
    letter-spacing: 0.12em;
    padding: var(--space-md) 0;
    border-bottom: 1px solid rgba(168, 133, 61, 0.08);
    white-space: nowrap;
  }

  .nav__link:last-child {
    border-bottom: none;
  }

  .nav__link::after {
    display: none;
  }

  .nav__link--active {
    color: var(--nav-text-hover);
    background: rgba(168, 133, 61, 0.06);
    margin: 0 calc(-1 * var(--space-lg));
    padding-left: var(--space-lg);
  }

  /* ── 汉堡菜单按钮 ── */
  .nav__hamburger {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    width: 36px;
    height: 36px;
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    background: transparent;
    cursor: pointer;
    transition:
      border-color var(--duration-fast),
      background var(--duration-fast);
  }

  .nav__hamburger:hover {
    border-color: var(--gold-border);
    background: var(--gold-dim);
  }

  .nav__hamburger-line {
    display: block;
    width: 20px;
    height: 2px;
    background: var(--nav-text);
    border-radius: 1px;
    transform-origin: center;
    transition:
      transform var(--duration-base) var(--ease-out),
      opacity var(--duration-base) var(--ease-out),
      background var(--duration-fast);
  }

  .nav__hamburger:hover .nav__hamburger-line {
    background: var(--nav-text-hover);
  }

  /* 汉堡菜单 → X 动画 */
  .nav__hamburger--open .nav__hamburger-line:nth-child(1) {
    transform: translateY(3.5px) rotate(45deg);
  }

  .nav__hamburger--open .nav__hamburger-line:nth-child(2) {
    transform: translateY(-3.5px) rotate(-45deg);
  }
}

/* ── 遮罩层 ── */
.nav__overlay {
  position: fixed;
  inset: 0;
  top: var(--nav-height);
  z-index: 99;
  background: var(--nav-overlay-bg);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-base) var(--ease-out);
}

.nav__overlay--visible {
  opacity: 1;
  pointer-events: auto;
}


/* ═══════════════════════════════════════════
   尊重 prefers-reduced-motion
   ═══════════════════════════════════════════ */

@media (prefers-reduced-motion: reduce) {
  .nav__menu,
  .nav__overlay,
  .nav__link::after,
  .nav__hamburger-line {
    transition-duration: 0.01ms !important;
  }
}