/* ========================================
   HEADER STYLES
   BookPulseZone - Literary E-commerce
   ======================================== */

/* Skip Link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: var(--color-background);
  padding: var(--space-2) var(--space-4);
  z-index: 100;
  transition: top var(--transition-fast);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  text-decoration: none;
}

.skip-link:focus {
  top: 0;
}

/* Header Layout */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-secondary-light);
  padding: var(--space-4) 0;
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
}

/* Logo */
.site-logo {
  font-family: var(--font-serif);
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  flex-shrink: 0;
  transition: color var(--transition-fast);
}

.site-logo:hover {
  color: var(--color-primary-hover);
}

/* Navigation */
.primary-navigation {
  display: flex;
  align-items: center;
}

.nav-list {
  display: flex;
  list-style: none;
  gap: var(--space-8);
  margin: 0;
  padding: 0;
}

.nav-link {
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text);
  text-decoration: none;
  padding: var(--space-2) 0;
  position: relative;
  transition: color var(--transition-fast);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-secondary);
  transition: width var(--transition-base);
}

.nav-link:hover {
  color: var(--color-primary);
}

.nav-link:hover::after {
  width: 100%;
}

/* Header Actions */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius-md);
  color: var(--color-text);
  background: transparent;
  border: none;
  cursor: pointer;
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.icon-btn:hover {
  background-color: var(--color-neutral-100);
  color: var(--color-primary);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 2.5rem;
  height: 2.5rem;
  gap: 5px;
  background: transparent;
  border: none;
  cursor: pointer;
  z-index: calc(var(--z-sticky) + 10);
}

.hamburger-line {
  display: block;
  width: 24px;
  height: 2px;
  background-color: var(--color-text);
  transition: transform var(--transition-base), opacity var(--transition-base);
  transform-origin: center;
}

/* Mobile Styles */
@media (max-width: 768px) {
  .mobile-menu-toggle {
    display: flex;
    order: 3;
  }

  .primary-navigation {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: 80%;
    max-width: 320px;
    background-color: var(--color-surface);
    padding: calc(var(--space-20) + var(--space-4)) var(--space-6) var(--space-6);
    transform: translateX(100%);
    transition: transform var(--transition-slow), visibility var(--transition-slow);
    visibility: hidden;
    box-shadow: var(--shadow-xl);
    border-left: 1px solid var(--color-secondary-light);
    z-index: calc(var(--z-sticky) + 5);
  }

  .primary-navigation.is-open {
    transform: translateX(0);
    visibility: visible;
  }

  .nav-list {
    flex-direction: column;
    gap: var(--space-4);
  }

  .nav-link {
    font-size: var(--text-lg);
    padding: var(--space-3) 0;
    display: block;
  }

  .nav-link::after {
    display: none;
  }

  /* Hamburger Animation */
  .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }

  .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
    opacity: 0;
  }

  .mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }

  /* Backdrop */
  .site-header::before {
    content: '';
    position: fixed;
    inset: 0;
    background-color: rgba(26, 43, 60, 0.5);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-base), visibility var(--transition-base);
    z-index: calc(var(--z-sticky) - 1);
  }

  .site-header:has(.primary-navigation.is-open)::before {
    opacity: 1;
    visibility: visible;
  }
}

/* Focus styles enhancement */
.mobile-menu-toggle:focus-visible,
.icon-btn:focus-visible {
  outline: 2px solid var(--color-secondary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}