/* ============================================================
   BG Remover — Header & Navigation
   ============================================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: color-mix(in srgb, var(--bg-page) 88%, transparent);
  backdrop-filter: saturate(160%) blur(14px);
  -webkit-backdrop-filter: saturate(160%) blur(14px);
  border-bottom: 1px solid var(--border-default);
  transition: background-color var(--dur-base) var(--ease-standard);
}

.header-inner {
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 clamp(16px, 3vw, 32px);
  min-height: var(--header-height);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: var(--space-6);
}

/* Brand */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: var(--fw-bold);
  letter-spacing: -0.015em;
  color: var(--fg-primary);
  font-size: var(--fs-md);
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  flex-shrink: 0;
}

.brand-name {
  white-space: nowrap;
}

/* Primary nav */
.primary-nav {
  display: flex;
  justify-content: center;
  min-width: 0;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 4px;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  padding: 8px 14px;
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--fg-secondary);
  border-radius: var(--radius-pill);
  transition:
    background-color var(--dur-fast) var(--ease-standard),
    color var(--dur-fast) var(--ease-standard);
}

.nav-link:hover {
  color: var(--fg-primary);
  background: var(--bg-subtle);
}

.nav-link.is-active {
  color: var(--fg-primary);
  background: var(--bg-subtle);
}

/* Actions */
.header-actions {
  display: flex;
  align-items: center;
  gap: 4px;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  color: var(--fg-secondary);
  transition: background-color var(--dur-fast) var(--ease-standard), color var(--dur-fast) var(--ease-standard);
}

.theme-toggle:hover {
  background: var(--bg-subtle);
  color: var(--fg-primary);
}

.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }
[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* Mobile toggle */
.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  color: var(--fg-primary);
}

.nav-toggle:hover {
  background: var(--bg-subtle);
}

/* Mobile layout */
@media (max-width: 900px) {
  .header-inner {
    grid-template-columns: auto auto 1fr;
    gap: var(--space-3);
  }

  .nav-toggle {
    display: inline-flex;
  }

  .primary-nav {
    position: fixed;
    inset: var(--header-height) 0 auto 0;
    background: var(--bg-elevated);
    border-bottom: 1px solid var(--border-default);
    padding: var(--space-4);
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: transform var(--dur-base) var(--ease-standard), opacity var(--dur-base) var(--ease-standard);
    box-shadow: var(--shadow-lg);
    max-height: calc(100vh - var(--header-height));
    overflow-y: auto;
    z-index: var(--z-header);
  }

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

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
  }

  .nav-link {
    padding: 12px 16px;
    border-radius: var(--radius-md);
    font-size: var(--fs-base);
    justify-content: flex-start;
  }

  .header-actions .btn span {
    display: none;
  }
  .header-actions .btn {
    padding: 10px;
    width: 40px;
    height: 40px;
  }
}

@media (max-width: 480px) {
  .brand-name {
    font-size: var(--fs-sm);
  }
  .brand-mark svg {
    width: 28px;
    height: 28px;
  }
}