Ubuntu-18-04-Modify Login Screen Background Image

Foreword

I've been using Ubuntu 18.04 for a while now. With the Gnome desktop, Ubuntu 18.04 (nicknamed "Rabbit") actually looks quite good. After pairing it with a few GTK themes I customized, it feels absolutely delightful. The only slight downside is that after Ubuntu switched its login manager to GDM, there's no longer a straightforward way to change the login screen background. That just wouldn't do! So, after some tinkering, this article was born.

First, prepare an image

The dimensions of the image should be determined based on your screen resolution. Then, place the image in the /usr/share/backgrounds/ directory.

Modifying GDM's CSS File

For those working in front-end development, using Gnome would be a delightful experience. Themes, extensions, and various customization options can be explored extensively.

File Location

/etc/alternatives/gdm3.css

/*Find the default section*/
#lockDialogGroup {
  background: #2c001e url(resource:///org/gnome/shell/theme/noise-texture.png);
  background-repeat: repeat; 
}

/*Change it to*/
#lockDialogGroup {
  background: #2c001e url(file:///usr/share/backgrounds/mypicture.jpg);         
  background-repeat: no-repeat;
  background-size: cover;
  background-position: center; 
}

Note: The CSS code provided is for reference only. Those familiar with front-end development can create better effects according to their preferences. Don’t forget to share your creations when you do!

Restart

You can restart the system or restart the graphical interface. To avoid any hassle, it's recommended to just restart the system—it's quick either way.

About

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