Add support to control font colors about change-gdm-background

[thiggy01]

@jgabriel98, @vaskark
I like the idea, but the first ask Ubuntu answer just teach you how to change the background color of the small login box and the other link just show you how to change the color of the clock dialog font.
Both don't tell you how to change font colors or size of the login dialog box and I really don't know how to do it on the .css file.
If you have any idea on how to change the login dialog font color, size or face please write it here and I'm going to try to implement it somehow on my script.

[vaskark]

Changing font faces would be great, too :)

[jgabriel98]

I've done some research, and found those two links:
how to change gnome lockscreen font settings (color, size, etc)
how to change gdm3 login screen font settings

so now we know how to edit the css, i think that this is enought to edit the change-gdm-background script, and add font color feature (and font face too).

i don't know when, but i will try to acomplish this.

[jgabriel98]

oh, my bad then.

I will do some more research for this topic on the future