hugo-theme-next/assets/css/_common/outline/sidebar/sidebar-toc.scss

@if $toc_enable {
  .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 not $toc_wrap {
        white-space: nowrap;
      }
    }

    .nav {
      .nav-child {
        display: if($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;
        }
      }
    }
  }
}