.index-list-page {

  .page-header {
    @include core-48;
    padding: $gutter-half 0;

    .title {
      padding: 0;
      margin: 0;
      padding-top: 12px;
      padding-top: 1.2rem;
    }

    .label {
      color: $low-contrast;
      padding: 0;
      margin: 0;
      padding-bottom: 8px;
      padding-bottom: 0.8rem;
    }

    @include media(tablet){
      padding: $gutter*2 0 $gutter;
      width: 80%;
    }

  }

  .index-list-container {
    margin-left: 33.333%;
    
    h3 {
      @include core-19;
    }

    ul {
      li {
        list-style: none;
        border-bottom: 1px solid $light-keyline;
        @include core-19;
      }
    }
  }

}
.index-list-page {

  .page-header {
    @include core-48;
    padding: $gutter-half 0;

    .title {
      padding: 0;
      margin: 0;
      padding-top: 12px;
      padding-top: 1.2rem;
    }

    .label {
      color: $low-contrast;
      padding: 0;
      margin: 0;
      padding-bottom: 8px;
      padding-bottom: 0.8rem;
    }

    @include media(tablet){
      padding: $gutter*2 0 $gutter;
      width: 80%;
    }

  }
}

.index-list-container {
  margin-left: 33.333%;
  
  h3 {
    @include core-19;
  }
}

.index-list {
  li {
    list-style: none;
    border-bottom: 1px solid $light-keyline;
    @include core-19;
  }
}

Remove dependence on page class
Remove dependence on page class

Add index-list class