/* ============================================
   HEADER - Nicolo-Pro
   ============================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  height: var(--header-height);
  background: var(--color-header-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-header-border);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}
.site-header.is-scrolled { box-shadow: var(--shadow-md); }

.header__inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 100%; max-width: var(--container-max);
  margin: 0 auto; padding: 0 var(--container-padding);
}

/* === Logo === */
.header__logo { flex-shrink: 0; }
.header__logo a { display: flex; align-items: center; gap: var(--space-2); font-size: var(--text-h3); font-weight: var(--font-weight-bold); color: var(--color-primary); }
.header__logo img { height: 36px; width: auto; }

/* === Nav === */
.header__nav { display: flex; align-items: center; }
.header__nav .nav__list { display: flex; align-items: center; gap: 4px; list-style: none; margin: 0; padding: 0; }
.header__nav .nav__item { margin: 0; position: relative; }
.header__nav .nav__link,
.header__nav a { display: block; padding: 8px 14px; font-size: 14px; font-weight: var(--font-weight-medium); color: var(--color-text); border-radius: var(--radius-sm); transition: color var(--transition-fast); white-space: nowrap; text-decoration: none; }
.header__nav .nav__link:hover,
.header__nav a:hover { color: var(--color-heading); }
.header__nav .nav__item--current > .nav__link,
.header__nav .current-menu-item > a { color: var(--color-heading); font-weight: var(--font-weight-semibold); }

/* === Dropdown === */
.header__nav .nav__item--dropdown > .nav__link { display: flex; align-items: center; gap: 4px; }
.header__nav .menu-item-has-children > a::after { content: ''; display: inline-block; width: 6px; height: 6px; margin-left: 4px; border-right: 1.5px solid currentColor; border-bottom: 1.5px solid currentColor; transform: rotate(45deg) translateY(-2px); transition: transform var(--transition-fast); }
.header__nav .nav__dropdown,
.header__nav .sub-menu {
  position: absolute; top: 100%; left: 0; min-width: 180px;
  padding: 8px 0; background: var(--color-surface);
  border-radius: var(--radius-md); box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-border);
  opacity: 0; visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
  list-style: none; margin: 0; z-index: var(--z-dropdown);
}
.header__nav .nav__item--dropdown:hover > .nav__dropdown,
.header__nav .menu-item-has-children:hover > .sub-menu { opacity: 1; visibility: visible; transform: translateY(0); }
.header__nav .nav__dropdown-item,
.header__nav .sub-menu a {
  display: block; padding: 8px 16px;
  font-size: var(--text-small); font-weight: var(--font-weight-normal);
  color: var(--color-text-secondary); text-decoration: none;
  border-radius: 0; transition: color var(--transition-fast), background var(--transition-fast);
}
.header__nav .nav__dropdown-item:hover,
.header__nav .sub-menu a:hover { color: var(--color-heading); background: var(--color-gray-100); }

/* 隐藏HTML中的物理箭头图标（CSS箭头已经处理） */
.header__nav .dropdown-icon { display: none; }

/* === Header Actions === */
.header__actions { display: flex; align-items: center; gap: var(--space-2); }
.header__cta { display: inline-flex; align-items: center; gap: var(--space-2); padding: var(--space-2) var(--space-6); font-size: var(--text-small); font-weight: var(--font-weight-semibold); color: var(--color-white); background: var(--color-accent); border-radius: var(--radius-sm); transition: background var(--transition-fast), transform var(--transition-fast); white-space: nowrap; flex-shrink: 0; }
.header__cta:hover { background: var(--color-accent-hover); transform: translateY(-1px); }
.header__search-toggle { display: flex; align-items: center; justify-content: center; width: 36px; height: 36px; color: var(--color-text); background: none; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: color var(--transition-fast), background var(--transition-fast); }
.header__search-toggle:hover { color: var(--color-accent); background: var(--color-accent-pale); }
.header__menu-toggle { display: none; align-items: center; justify-content: center; width: 36px; height: 36px; color: var(--color-text); background: none; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: color var(--transition-fast), background var(--transition-fast); }
.header__menu-toggle:hover { color: var(--color-accent); background: var(--color-accent-pale); }

/* === Search Overlay === */
.header__search-overlay { position: fixed; inset: 0; z-index: var(--z-overlay); background: var(--color-overlay); display: flex; align-items: flex-start; justify-content: center; padding-top: 20vh; opacity: 0; visibility: hidden; transition: opacity var(--transition-base), visibility var(--transition-base); }
.header__search-overlay.is-active { opacity: 1; visibility: visible; }
.header__search-form { display: flex; width: 100%; max-width: 600px; margin: 0 var(--space-6); background: var(--color-surface); border-radius: var(--radius-md); box-shadow: var(--shadow-xl); overflow: hidden; }
.header__search-input { flex: 1; padding: var(--space-4) var(--space-6); font-size: var(--text-body); border: none; outline: none; background: transparent; color: var(--color-text); }
.header__search-input::placeholder { color: var(--color-text-muted); }
.header__search-close { position: absolute; top: var(--space-6); right: var(--space-6); width: 40px; height: 40px; display: flex; align-items: center; justify-content: center; font-size: 24px; color: var(--color-white); background: none; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: background var(--transition-fast); }
.header__search-close:hover { background: rgba(255,255,255,0.15); }

/* === Mobile Nav Panel === */
.mobile-nav { display: none; }
.mobile-nav__backdrop { position: fixed; inset: 0; z-index: calc(var(--z-overlay) - 1); background: var(--color-overlay); opacity: 0; visibility: hidden; transition: opacity var(--transition-base), visibility var(--transition-base); }
.mobile-nav.is-active .mobile-nav__backdrop { opacity: 1; visibility: visible; }
.mobile-nav__panel { position: fixed; top: 0; right: 0; bottom: 0; width: 300px; max-width: 85vw; z-index: var(--z-overlay); background: var(--color-surface); box-shadow: var(--shadow-xl); overflow-y: auto; transform: translateX(100%); transition: transform var(--transition-base); display: flex; flex-direction: column; }
.mobile-nav.is-active .mobile-nav__panel { transform: translateX(0); }
.mobile-nav__header { display: flex; align-items: center; justify-content: space-between; padding: var(--space-4) var(--space-6); border-bottom: 1px solid var(--color-border-light); flex-shrink: 0; }
.mobile-nav__close { display: flex; align-items: center; justify-content: center; width: 32px; height: 32px; color: var(--color-text-secondary); background: none; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: color var(--transition-fast), background var(--transition-fast); }
.mobile-nav__close:hover { color: var(--color-text); background: var(--color-gray-100); }
.mobile-nav__body { flex: 1; overflow-y: auto; padding: var(--space-4) var(--space-6); }
.mobile-nav__list { list-style: none; margin: 0; padding: 0; }
.mobile-nav__list li { border-bottom: 1px solid var(--color-border-light); }
.mobile-nav__list a, .mobile-nav__link { display: block; padding: var(--space-3) 0; font-size: var(--text-body); color: var(--color-text); transition: color var(--transition-fast); }
.mobile-nav__list a:hover, .mobile-nav__link:hover { color: var(--color-accent); }
.mobile-nav__list .sub-menu { padding-left: var(--space-4); display: none; list-style: none; margin: 0; }
.mobile-nav__list .sub-menu.open { display: block; }
.mobile-nav__list .sub-menu a { font-size: var(--text-small); color: var(--color-text-secondary); }
.mobile-nav__list .menu-item-has-children > a { display: flex; align-items: center; justify-content: space-between; }
.mobile-nav__list .menu-item-has-children > a::after { content: '+'; font-size: 18px; font-weight: var(--font-weight-normal); color: var(--color-text-muted); transition: transform var(--transition-fast); }
.mobile-nav__list .menu-item-has-children.open > a::after { content: '\2212'; }
.mobile-nav__footer { padding: var(--space-4) var(--space-6); border-top: 1px solid var(--color-border-light); flex-shrink: 0; }
.mobile-nav__cta { display: flex; align-items: center; justify-content: center; gap: var(--space-2); width: 100%; padding: var(--space-3) var(--space-6); font-size: var(--text-body); font-weight: var(--font-weight-semibold); color: var(--color-white); background: var(--color-accent); border-radius: var(--radius-md); transition: background var(--transition-fast); }
.mobile-nav__cta:hover { background: var(--color-accent-hover); }

/* === Responsive === */
@media (max-width: 1024px) {
  .header__nav, .header__cta { display: none; }
  .header__menu-toggle { display: flex; }
  .mobile-nav { display: block; }
}
@media (max-width: 768px) {
  .site-header { height: var(--header-height-mobile); }
  .header__inner { padding: 0 var(--space-4); }
}