css

const commentItemWrap = css`
  padding: 20px 24px 0 24px;
  &:hover{
    background: #F7F8F9;
    .bts{
      display: block;
    }
  }
`
<div className={commentItemWrap}>
     <ButtonGroup className={cx('bts', css`display: none`)}>
    <Button>回复</Button>
    <Button type="danger">删除</Button>
  </ButtonGroup>
</div>