ach2">
  <template>
    <style>
      :host {
        display: block;
        border: 1px dashed tomato;
        padding: 4px;
      }

      x-attach3 > ::slotted(.add2) {
        box-sizing: border-box;
        height: 20px;
        background: gray;
        border: 2px solid yellow;
      }
    </style>
    <x-attach3><slot></slot></x-attach3>
    <template is="dom-if" if="{{shouldIf(done.count)}}">
      <x-attach1></x-attach1>
    </template>
  </template>
  <script type="module">
import '../../polymer