roadmap/quartz/components/styles/toc.scss

details.toc {
  & summary {
    cursor: pointer;

    list-style: none;
    &::marker, &::-webkit-details-marker {
      display: none;
    }

    & > * {
      display: inline-block;
      margin: 0;
    }

    & > h3 {
      font-size: 1rem;
    }
  }
    
  & ul {
    list-style: none;
    margin: 0.5rem 0;
    padding: 0;
    & > li > a {
      color: var(--dark);
      opacity: 0.35;
      transition: 0.5s ease opacity;
      &.in-view {
        opacity: 0.75;
      }
    }
  }

  @for $i from 0 through 6 {
    & .depth-#{$i} {
      padding-left: calc(1rem * #{$i});
    }
  }
}