/* ============================================================
   导航栏样式
   ============================================================ */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  transition: box-shadow var(--transition-base);
}

/* 滚动后：毛玻璃背景浮现（用 ::before 避免 backdrop-filter 影响 fixed 子元素定位） */
.nav.scrolled::before {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  background: rgba(10, 14, 26, 0.88);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  transition: background var(--transition-base), backdrop-filter var(--transition-base);
}

.nav.scrolled {
  box-shadow: 0 1px 0 var(--color-border), 0 8px 32px rgba(0,0,0,0.4);
}

/* 亮色模式：导航栏透明 */
[data-theme="light"] .nav.scrolled::before {
  background: rgba(240, 244, 255, 0.92);
}

[data-theme="light"] .nav.scrolled {
  box-shadow: 0 1px 0 rgba(79,142,247,0.15), 0 8px 24px rgba(79,142,247,0.08);
}

/* 亮色：移动端菜单面板 */
[data-theme="light"] .nav__menu.mobile-open {
  background: rgba(240, 244, 255, 0.98);
}

/* 亮色：汉堡线条 */
[data-theme="light"] .nav__hamburger span {
  background: var(--color-text);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

/* ---------- Logo ---------- */
.nav__logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-size: var(--text-lg);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--color-text);
  flex-shrink: 0;
}

.nav__logo-icon {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-lg);
  box-shadow: 0 0 16px var(--color-primary-glow);
}

.nav__logo-text span {
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ---------- 菜单 ---------- */
.nav__menu {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav__item {
  position: relative;
}

.nav__link {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 0.5rem 0.875rem;
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-sub);
  transition: var(--transition-fast);
  white-space: nowrap;
}

.nav__link:hover,
.nav__link.active {
  color: var(--color-text);
  background: rgba(255,255,255,0.05);
}

/* 亮色模式：顶层导航链接 */
[data-theme="light"] .nav__link {
  color: var(--color-text-sub);
}

[data-theme="light"] .nav__link:hover,
[data-theme="light"] .nav__link.active {
  color: var(--color-text);
  background: rgba(45, 110, 224, 0.07);
}

.nav__link svg {
  width: 14px;
  height: 14px;
  transition: transform var(--transition-fast);
  flex-shrink: 0;
}

.nav__item:hover .nav__link svg { transform: rotate(180deg); }

/* ---------- 下拉菜单 ---------- */
.nav__dropdown {
  position: absolute;
  top: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%);
  min-width: 180px;
  background: rgba(13, 20, 36, 0.95);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: var(--space-2);
  opacity: 0;
  visibility: hidden;
  transform: translateX(-50%) translateY(-8px);
  transition: opacity var(--transition-fast), transform var(--transition-fast),
              visibility var(--transition-fast);
  box-shadow: var(--shadow-card), 0 0 40px rgba(0,0,0,0.3);
}

/* 亮色模式：下拉面板改为白色毛玻璃 */
[data-theme="light"] .nav__dropdown {
  background: rgba(255, 255, 255, 0.96);
  box-shadow: 0 8px 32px rgba(79, 142, 247, 0.12), 0 2px 8px rgba(0,0,0,0.06);
}

[data-theme="light"] .nav__dropdown-link {
  color: var(--color-text-sub);
}

[data-theme="light"] .nav__dropdown-link:hover {
  color: var(--color-primary);
  background: rgba(45, 110, 224, 0.07);
}

[data-theme="light"] .nav__dropdown-link-icon {
  background: rgba(45, 110, 224, 0.08);
}

.nav__item:hover .nav__dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.nav__dropdown-link {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: 0.6rem var(--space-3);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-text-sub);
  transition: var(--transition-fast);
}

.nav__dropdown-link:hover {
  color: var(--color-primary);
  background: rgba(79,142,247,0.08);
}

.nav__dropdown-link-icon {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  background: rgba(79,142,247,0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-base);
  flex-shrink: 0;
}

/* ---------- 右侧行动按钮 ---------- */
.nav__cta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* ---------- 汉堡按钮（移动端） ---------- */
.nav__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-2);
  cursor: pointer;
}

.nav__hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-text);
  border-radius: var(--radius-full);
  transition: var(--transition-fast);
}

.nav__hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__hamburger.open span:nth-child(2) { opacity: 0; }
.nav__hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- 移动端菜单面板 ---------- */
@media (max-width: 900px) {
  .nav__menu, .nav__cta .btn--outline { display: none; }
  .nav__hamburger { display: flex; }

  .nav__menu.mobile-open {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-1);
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 999;
    background: rgba(10, 14, 26, 0.97);
    backdrop-filter: blur(20px);
    padding: var(--space-6);
    overflow-y: auto;
  }

  .nav__link {
    width: 100%;
    font-size: var(--text-base);
    padding: 0.75rem var(--space-3);
  }

  .nav__dropdown {
    position: static;
    transform: none;
    opacity: 1;
    visibility: visible;
    background: transparent;
    border: none;
    box-shadow: none;
    padding-left: var(--space-4);
    min-width: unset;
  }

  .nav__item:hover .nav__dropdown {
    transform: none;
  }
}

/* ══════════════════════════════════════════
   主题切换按钮
══════════════════════════════════════════ */
.theme-toggle {
  position: relative;
  width: 52px;
  height: 28px;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  background: var(--color-bg-card);
  backdrop-filter: blur(8px);
  cursor: pointer;
  transition: border-color var(--transition-base), background var(--transition-base),
              box-shadow var(--transition-base);
  flex-shrink: 0;
  overflow: hidden;
}

.theme-toggle:hover {
  border-color: var(--color-primary);
  box-shadow: 0 0 12px var(--color-primary-glow);
}

/* 滑块 */
.theme-toggle__track {
  position: absolute;
  inset: 3px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 4px;
}

/* 滑动圆球 */
.theme-toggle__thumb {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  box-shadow: 0 2px 8px var(--color-primary-glow);
  transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1),
              background 0.4s;
  z-index: 1;
}

/* 亮色时：thumb 滑到右边 */
[data-theme="light"] .theme-toggle__thumb {
  transform: translateX(24px);
  background: linear-gradient(135deg, #f7b731, #f5a623);
  box-shadow: 0 2px 8px rgba(247,183,49,0.4);
}

/* 图标 */
.theme-toggle__icon {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  font-size: 12px;
  line-height: 1;
  transition: opacity 0.3s, transform 0.3s;
  pointer-events: none;
}

/* 月亮 — 暗色时在右 */
.theme-toggle__moon {
  right: 5px;
  opacity: 1;
}

/* 太阳 — 亮色时在左 */
.theme-toggle__sun {
  left: 5px;
  opacity: 0;
}

[data-theme="light"] .theme-toggle__moon { opacity: 0; }
[data-theme="light"] .theme-toggle__sun  { opacity: 1; }

/* 亮色模式下整体切换按钮背景变浅 */
[data-theme="light"] .theme-toggle {
  background: rgba(255,255,255,0.7);
  border-color: rgba(79,142,247,0.25);
}