.tsai-series-nav {
  margin: 2.5rem 0;
  border: 1px solid #333;
  border-radius: 8px;
  background: #1C1C1C;
  overflow: hidden;
}

.tsai-series-nav__header {
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid #333;
}

.tsai-series-nav__title {
  font-size: 1.1rem;
  font-weight: 600;
  color: #F5F5F5;
}

.tsai-series-nav__subtitle {
  margin-top: 0.25rem;
  font-size: 0.85rem;
  color: #9A9A9A;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.tsai-series-nav__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.tsai-series-nav__item {
  border-bottom: 1px solid #222;
}

.tsai-series-nav__item:last-child {
  border-bottom: none;
}

.tsai-series-nav__link {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.85rem 1.5rem;
  color: #F5F5F5;
  text-decoration: none;
  transition: background 150ms ease;
}

a.tsai-series-nav__link:hover {
  background: #2a2a2a;
  color: #8A6EFF;
}

.tsai-series-nav__part-num {
  flex-shrink: 0;
  width: 1.75rem;
  height: 1.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: #333;
  font-size: 0.8rem;
  font-weight: 600;
  color: #9A9A9A;
}

.tsai-series-nav__item.is-current .tsai-series-nav__part-num {
  background: #8A6EFF;
  color: #111;
}

.tsai-series-nav__part-title {
  font-size: 0.95rem;
}

.tsai-series-nav__item.is-current .tsai-series-nav__part-title {
  font-weight: 600;
  color: #8A6EFF;
}

a.tsai-series-nav__link:hover .tsai-series-nav__part-num {
  background: #8A6EFF;
  color: #111;
}