Why is the GUI not showing in Ubuntu 16.04 x64?

Question

css

Hello! I have Ubuntu 16.04 x64 with Unity installed on my computer. I decided to put DE Cinnamon, put it, everything started. Then uninstalled Unity
sudo apt remove unityand rebooted the PC. Now at startup I see an error:
The system is running in low-graphical mode. Your screen,graphic-card and input device settings could not be detected correctly. You will need to configure these yourself.
As I understand it, along with Unity, I lost some settings that I have to re-install. How to restore the work of the graphical interface (Cinnamon)?
UPD: Apparently, he demolished unity-greeter along with unity, but for some reason it is not possible to edit the /etc/lightdm/lightdm.conf file (not enough rights) even from root.

Answer 1

That's right, tr ignores border styles, set to cells, with table collapse:

table {
  border-collapse: collapse;
}

th, td {
  border-bottom: ...;
}

Answer 2

Why such difficulties? ::before help

Answer 3

sudo apt-get install ubuntu-desktop
This will install a stock Ubuntu environment, including everything you need to work with graphics.