Hello,
When you upload demo content, there a few rows that have a background image, these images are external, so you just need to remove these images, or better remove the pages from the demo you do not use. And check pages which you use, remove all the background images.
Make sure your site URL is correctly inserted in the Settings > Genera, if your site is https, there should be also https.
CSS generator disables the CSS that is not used, you can use it if you need: https://xtemos.com/docs/woodmart/css-generator/
Best Regards