This is an MDM login theme made to fit with the Zukitwo cinnamon theme.
- Extract and move the folder into usr/share/mdm/html-themes.
- Select the theme from system settings-->login window.
All you have to do to change the wallpaper is to switch out the "bg.png" image from the image folder!
In case your image ends with ".jpg" or you want another name just open the "theme.css" file and search for "bg.png" and rename it!
I recommend you also play around with CSS filters!Using them you can add blur to your wall, and all sorts of other effects
I have isolated most rule sets from the bootstrap file and added them to the "theme.css" file.
Also added in-line comments.
Now you can style the whole things using only that css file!