/* Header Styles */

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 64px;
  background-color: var(--color-canvas);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-4);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.header-container > div {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.header-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-ink);
  text-decoration: none;
  flex-shrink: 0;
}

.header-logo:hover {
  text-decoration: none;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.header-link {
  color: var(--color-ink-subtle);
  font-size: 0.875rem;
  font-weight: 500;
  padding: var(--space-2) 0;
  border-bottom: 2px solid transparent;
  transition: color 0.15s ease;
}

.header-link:hover {
  color: var(--color-ink);
  text-decoration: none;
}

.header-link.active {
  color: var(--color-ink);
  border-bottom-color: var(--color-link);
}

.theme-toggle-btn {
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
  border-radius: var(--radius-md);
  color: var(--color-ink);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color 0.15s ease;
}

.theme-toggle-btn:hover {
  background-color: var(--color-canvas-subtle);
}

.theme-icon {
  width: 20px;
  height: 20px;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 44px;
  height: 44px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
  border-radius: var(--radius-md);
  gap: 5px;
}

.mobile-menu-toggle:hover {
  background-color: var(--color-canvas-subtle);
}

.hamburger-line {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

/* Mobile Menu Open State */
.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);
}

/* Responsive Styles */
@media (max-width: 768px) {
  .header {
    height: 56px;
  }

  .header-container {
    padding: 0 var(--space-3);
  }

  .mobile-menu-toggle {
    display: flex;
  }

  .header-nav {
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-canvas);
    flex-direction: column;
    align-items: stretch;
    padding: var(--space-4);
    gap: var(--space-2);
    transform: translateX(100%);
    transition: transform 0.25s ease;
    z-index: 99;
    overflow-y: auto;
  }

  .header-nav.is-open {
    transform: translateX(0);
  }

  .header-link {
    font-size: 1.125rem;
    padding: var(--space-3) var(--space-2);
    border-bottom: none;
    border-radius: var(--radius-md);
    text-align: center;
  }

  .header-link:hover {
    background-color: var(--color-canvas-subtle);
  }

  .header-link.active {
    background-color: var(--color-link-subtle);
    color: var(--color-link);
    border-bottom-color: transparent;
  }

  .theme-toggle-btn {
    align-self: center;
    padding: var(--space-3);
    margin-top: var(--space-2);
  }

  .theme-icon {
    width: 24px;
    height: 24px;
  }

  .header-nav .btn {
    width: 100%;
    margin-top: var(--space-4);
    padding: var(--space-3);
    font-size: 1rem;
  }
}

@media (max-width: 640px) {
  .header-logo {
    font-size: 1.125rem;
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  .header-nav {
    transition: none;
  }

  .hamburger-line {
    transition: none;
  }
}