Bootstap 4 css for Trix

trix-bootstrap4.scss

trix-toolbar {
  margin-bottom: 1em;
  .trix-button-row {
    @extend .btn-toolbar;
    justify-content: space-between;
    .trix-button-group {
      @extend .btn-group;
      .trix-button {
        @extend .btn;
        @extend .btn-outline-secondary;
      }
      .trix-active {
        @extend .active;
      }
    }
  }
}
trix-editor {
  @extend .form-control;
  min-height: 8.5em;
}