Background: url() cannot be displayed normally, and the layer relationship is changed. z-index: incorrect

[ghrst6688]

Background:url() cannot be displayed normally, and the layer relationship is changed. z-index: incorrect
【背景图片background; url()不能正常显示，图层关系被改变z-index:不正确】
Because the code cannot be sent normally, please check the website

https://sangzizhuxue.cn/static/js/html2img.html

Who can modify html2canvas.js correctly and process this page normally?

https://sangzizhuxue.cn/static/js/html2img.html

https://sangzizhuxue.cn/static/js/html2img.html

https://sangzizhuxue.cn/static/js/html2img.html