Incorrect (exposing DOM to consumers):

// my-library/src/components/data-grid.gjs
export class DataGrid extends Component {
  <template>
    <div class="data-grid">
      <div class="data-grid__header">
        <button class="sort-button" data-column="name">Name</button>
      </div>
      <div class="data-grid__body">
        {{#each @rows as |row|}}
          <div class="data-grid__row">{{row.name}}</div>
        {{/each}}
      </div>
    </div>
  </template>
}