More than 2 background images

[michielbles]

I would like to add more than 2 background images to this page: http://kamer-vragen.com/appartementamsterdam1.html

I have added a 3rd slide with the same code as slide 2, but for some reason, the background image on the 3rd slide (the one below the kitchen photo) will not appear on Safari 5.0 (on my old Mac), but does appear on Safari 7.0 (my new Mac). On my (office) Windows machine it's visible on Firefox, not on Chrone. Anyone has ideas how to fix this?