How to change the background color of the notifications popup? [duplicate]

Question

I have installed the Flatabulous theme and the Paper icons on my OS but unfortunately the background color of the notifications popup is transparent, which is pretty hard to read it sometimes. How can I change the color of the popup and turn it into black or something different?

thanks in advance for the answers!

ps: I have already read this but it was not useful because I don't know where is located the file that they mention in the post. Anyways, here is an example of my notifications popup: as you can see it's hard to see, almost impossible...

Answer 1

Just as the post you linked says you can open the file by entering

sudo scratch-text-editor /usr/share/themes/elementary/gtk-3.0/apps.css

in the terminal. Once it's open look for the section that starts with this

/*******
* Gala *
*******/

The default CSS code looks like this:

.gala-notification {
    border: none;
    border-radius: 4px;
    background-color: transparent;
    background-image:
        linear-gradient(
            to bottom,
            @bg_color,
            @bg_color 80%,
            shade (
                @bg_color,
                0.94
            )
        );

You need to change it to this:

.gala-notification {
    border: none;
    border-radius: 4px;
    background-color: transparent;
    background-image:
        linear-gradient(
            to bottom,
            @bg_color,
            @bg_color 80%,
            shade (
                @bg_color,
                0.94
            )
        );

.gala-notification GtkLabel {
    color: #fff;
 }

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