postcss-bem child 选择器

Question

<div class="page-button__group">
    <button disabled size="large">default</button>
    <button disabled size="large" type="primary">primary</button>
    <button disabled size="large" type="danger">danger</button>
</div>

<style lang="scss">
    @component-namespace page {
        @component button {
          padding: 0 15px 15px;

          @descendent group {
            margin-bottom: 15px;
                button {
                  margin-bottom: 15px;
                }
              }
           }
      }
</style>

使用postcss-bem子元素button样式怎么写，button没有class.
输出类似于这种：

.page-button-group, .page-button-group>* {
    margin-bottom: 15px;
}