(dev) Zebra not visible using XAMPP for Linux 1.7.7

using XAMPP as Server on Linux (Mint - Ubuntu) zebra is not visible but usable anyway:
       Firebug inspection on the css of the zebra reveals "Failed to load given URL" url("../img/zebra-background.svg")

Using python SimpleHTTPServer it's ok.
Using the same version of XAMPP on Windows it's ok.
