html2canvas转pdf分页隔断问题处理

//html代码
<div id="demo">
    <div class="jy-page">...</div>
</div>


//下载前处理的函数
renderOverpageClum () {
        let demoHeight = $('#demo').height()
        let pageWidth = $('#demo').width()
        let pageHeight = pageWidth / 595.28 * 841.89   // 计算每页的高度
        let pageNum = Math.ceil((demoHeight - 100)/(pageHeight - 100))
        $('.jy-page').attr('style', 'height:'+pageHeight+'px;' + pageNum * pageWidth + 'px;column-count: '+pageNum+'');
        var baseDom = $('.jy-page').eq(0)
        console.log((demoHeight - 100)/(pageHeight - 100))
        console.log(pageNum)
        console.log('每页宽度：'+ pageWidth)
        console.log('每页高度：'+ pageHeight)
        if (pageNum > 1) {
          for (var i = 1; i < pageNum; i++) {
            $('#demo').append(baseDom.clone().css('left','-' + pageWidth * i + 'px'))
          }
        }
        $('.table-item-first').each(function () {
          if ($(this).text().length > 5) {
            let pipHeight = $(this).height()
            $(this).nextAll().height(pipHeight).css({'line-height':pipHeight + 'px'})
          } else {
            let pipHeight = $(this).height()
            $(this).nextAll().height(pipHeight).css({'line-height':pipHeight + 'px'})
          }
        })
        console.log('文档高度：'+ $('#demo').height())
      }


//css样式
#demo {
    min- 920px;
    max- 1190px;
    margin: 0 auto;
    overflow: hidden;
    box-sizing: border-box;
  }
.jy-page {
    box-sizing: border-box;
    column-gap:0px;
    column-fill: auto;
    padding: 50px 0;
    position: relative;
  }

handleDown() {
        this.pod = true
        this.$nextTick().then(() => {
          this.renderOverpageClum()
          htmlToPdf.downloadPDF(document.querySelector('#demo'), 'download')
          this.resetClumStyle()
        })
      },
      handlePreview() {
        this.pod = true
        this.$nextTick().then(() => {

          $('.table-item-first').each(function () {
            let pipHeight = $(this).height()
            $(this).nextAll().height(pipHeight).css({'line-height':pipHeight + 'px'})
          })

          htmlToPdf.previewImg(document.querySelector('#demo')).then(res => {
            this.previewUrl = res
          })
          this.previewImgShow = true
        })

      },