===== LightDM customization =====
==== Theme ====

In order to style the background and theme of the LightDM login screen edit the /etc/lightdm/lightdm-gtk-greeter.conf file as follows
  
  #nano /etc/lightdm/lightdm-gtk-greeter.conf

  [greeter]
  background=/home/oscar/Pictures/Katwijk-Silouet-edge-grain1.jpg
  theme-name=Adwaita-dark

=== Resolution ===
In a VM the lightDM could start with a wrong/low resolution. 
Add the following line to /etc/lightdm/lightdm.conf:

<code>
# nano /etc/lightdm/lightdm.conf

[Seat:*]
display-setup-script=xrandr -s 1920x1080
#type=xlocal
</code>