hexo-theme-next/source/css/_common/outline/sidebar/sidebar-toc.styl

.post-toc {
  font-size: $font-size-small;

  ol {
    list-style: none;
    margin: 0;
    padding: 0 2px 5px 10px;
    text-align: left;

    > ol {
      padding-left: 0;
    }

    a {
      transition: all $transition-ease;
    }
  }

  .nav-item {
    line-height: 1.8;
    overflow: hidden;
    text-overflow: ellipsis;

    if (!hexo-config('toc.wrap')) {
      white-space: nowrap;
    }
  }

  .nav {
    .nav-child {
      display: hexo-config('toc.expand_all') ? block : none;
    }

    .active > .nav-child {
      display: block;
    }

    .active-current > .nav-child {
      display: block;

      > .nav-item {
        display: block;
      }
    }

    .active > a {
      border-bottom-color: $sidebar-highlight;
      color: $sidebar-highlight;
    }

    .active-current > a {
      color: $sidebar-highlight;

      &:hover {
        color: $sidebar-highlight;
      }
    }
  }
}