If you are testing the local machine without using a web server (i.e. if the URL of your page in FF starts with " file:// ", this URL will not work. You need to specify the relative path to the image, because otherwise it will look for this image in the root directory of your hard drive.
So, if your files look like this:
/some/path/html/index.html /some/path/html/images/bgimage.jpg
Your code will look like this:
background-image: url('images/bgimage.jpg');
Tyson
source share