I use all of these:
1. body{ background-image: url('example.png') background-repeat: repeat;
2. body{ background-image: url('assets/example.png') background-repeat: repeat;
3. body{ background-image: url(<%= asset_path 'example.png') background-repeat: repeat;
4. body{ background-image: image-url(<%= asset_path 'example.png' %>) background-repeat: repeat;
5. body{ background-image: image-url('example.png') background-repeat:repeat;
6. body{ background-image: image-url('assets/example.png') background-repeat:repeat;
run assets:precompile
not working all, how to solve this problem, why not working?