header {
  padding: 0;
  border-bottom: 1px solid #e5e5e5;
  background: #ffffff;
  position: sticky;
  top: 0;
  z-index: 100;
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  line-height: 1.6;
  font-size-adjust: none;
}

header .nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  min-height: 3.5rem;
}

header .nav-left {
  display: flex;
  align-items: baseline;
  gap: 1rem;
}

header .nav-logo-img {
  display: flex;
  align-self: center;
}

header .nav-logo-img img {
  width: 1.5rem;
  height: 1.5rem;
}

header .nav-logo-text {
  font-weight: 600;
  font-size: 0.9rem;
  color: #000000;
  text-decoration: none;
  white-space: nowrap;
}

header .nav-link {
  color: #6b7280;
  text-decoration: none;
  font-size: 0.85rem;
}

header .nav-link:hover {
  color: #000000;
}

header .nav-right {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 0.85rem;
}

header .btn {
  padding: 0.4rem 1rem;
  border: 1px solid #d1d5db;
  background: transparent;
  color: #6b7280;
  text-decoration: none;
  font-size: 0.85rem;
  border-radius: 0.375rem;
  cursor: pointer;
  transition: all 0.15s;
  font-family: inherit;
}

header .btn:hover {
  border-color: #000000;
  color: #000000;
}

header .btn-active {
  background: #f5f5f5;
  color: #000000;
  border-color: #d0d0d0;
  cursor: default;
  font-weight: 500;
}

header .btn-active:hover {
  background: #f5f5f5;
  border-color: #d0d0d0;
}

header .btn-primary {
  background: #000000;
  color: #ffffff;
  border-color: #000000;
}

header .btn-primary:hover {
  opacity: 0.85;
}

header .btn .btn-text {
  display: inline;
}

@media (max-width: 768px) {
  header .nav-container {
    padding: 0.75rem 1rem;
  }

  header .nav-left {
    gap: 0.5rem;
  }

  header .nav-logo-text {
    font-size: 0.8rem;
    margin-right: 0.5rem;
  }

  header .nav-link {
    font-size: 0.75rem;
  }

  header .btn .btn-text {
    display: none;
  }

  header .btn {
    padding: 0.3rem 0.6rem;
  }

  header .nav-right {
    gap: 2px;
  }
}

/* Dark mode */
@media (prefers-color-scheme: dark) {
  header {
    background: #1a1a1a;
    border-bottom-color: #333;
  }

  header .nav-logo-text {
    color: #f3f4f6;
  }

  header .nav-link {
    color: #9ca3af;
  }

  header .nav-link:hover {
    color: #f3f4f6;
  }

  header .btn {
    background: #2a2a2a;
    border-color: #333;
    color: #9ca3af;
  }

  header .btn:hover {
    background: #333;
    border-color: #444;
    color: #f3f4f6;
  }

  header .btn-active {
    background: #333;
    color: #f3f4f6;
    border-color: #444;
  }

  header .btn-active:hover {
    background: #333;
    border-color: #444;
  }

  header .btn-primary {
    background: #f3f4f6;
    color: #111;
    border-color: #f3f4f6;
  }

  header .btn-primary:hover {
    background: #d1d5db;
  }
}