We've sent you a few messages about this recently again @AlexD - it seems Blocs app can't export Pulse sites to a sub-folder currently.
e.g. yourdomain.com/test
If you installed the site in the root (e.g. yourdomain.com) it would have worked perfectly with CSS and image links.
Thanks to @Raimo for helping detect this issue.
We don't have control over this as we don't make Blocs - but have contacted them and they will get this fixed most likely for their next update.
Related issue: