How to use GTK theme colors in scss?

[the-argus]

By default, widget's background color matches my GTK theme. however, I added the following scss:

window {
    background-color: rgba(0.0, 0.0, 0.0, 0.0);
}

This means that the window is nicely transparent, and I can set widgets' background colors to be opaque colors, and give them margins, which results in a floating effect. However, I can only manually set these colors, and then would not change if I changed my gtk theme. Is there some gtk scss with color-defines I could import, or something like that?