.Navigation {
  position: sticky;
  width: 190px;
  padding-left: 16px; /* 左侧留给导轨 */
}

.Navigation .rail {
  position: absolute;
  left: 6px;
  top: 0;
  bottom: 0;
  width: 6px;
  background: #EBEBEB; /* 浅灰导轨 */
}

.Navigation .indicator {
  position: absolute;
  left: 6px;
  width: 6px;
  background: #1f1f1f; /* 深色活动段 */
  border-radius: 2px;
  transition: top 0.25s ease, height 0.25s ease;
}

.Navigation ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.Navigation .nav-item {
  padding: 3px 12px;
  font-size: 15px;
  cursor: pointer;
}

.Navigation .nav-item a {
  color: inherit;
  text-decoration: none;
}

.Navigation .nav-item.active {
  font-weight: 700;
}

.Navigation .nav-item.active a {
  text-decoration: underline;
  text-decoration-color: #446DC0;
  text-underline-offset: 4px;
}