The quotes are not the issue. I can get featured images to work, but my understanding is the img code for responsive images is quite complex. I don’t know how this example code can be converted to work as a background-image as it doesn’t use an img tag, it uses a URL. I’ve tried a few options but nothing works.
@andrewmc the closest you can get with CSS is the image-set() function but that is only for resolution (DPI), not responsive images as per HTML’s srcset attribute. It also has poor browser support.
If you need responsive images then you’d need to change your design to not use background images.
My friend used to create a code on his PC. The script checked the folder with a collection of photo (wallpapers) on his computer and then changed them periodically.
He was so obsessed with new illustrations that he actually created an online https://wallpapercosmos.com/ library specificly for this purpose. So, if you think that it is not manageable – it is.
Do you want me to ask my pal about the code he used?