main.css

/* Style for Gtk.Frame */
frame {
    border: 3px solid #0000ff;
    border-radius: 20px;
    color: #ff0000;
    background-color: #606060;

}

/* Style for Gtk.Box */
box {
    border: 2px solid #ffffff;
    border-radius: 10px;
    background-color: #000000;
    padding: 0px;
    margin: 10px;
    color: #ffffff;
    opacity: 0.8;
}

box > button {
    all: unset;
}

box > revealer {
    border-width: 0px;
}

revealer > box {
    border: 2px solid rgba(0, 255, 255, 0.3);
    border-radius: 5px;
    background-color: #202020;

}

/* Style for Gtk.label in Gtk.Box */
box > label {
    color: #00ff00;
    margin: 5px;
}

scale {
    /* top | right | bottom | left */
    margin: 15px;
}


progressbar {
    /* top | right | bottom | left */
    margin: 20px;
}

/* Prograss background bar */
progressbar > trough {
    min-height: 8px;
    background-color: #007070;
}

/* Prograss */
progressbar > trough > progress {
    min-height: 10px;
    background-color: #00ffff;
}

/* Style for Gtk.Paned Separator */
paned > separator {
  background-image: linear-gradient(to bottom, #00ffff, #00ffff);
  background-size: 2px 2px;
}

/* Style for Gtk.Separator */

box > separator {
  background-color: rgba(0, 255, 255, 0.3);
  min-width: 2px;
  min-height: 2px;
  margin: 5px;
}

textview.view {
    margin: 10px;
    padding: 10px;
    border: 2px solid rgba(0, 255, 255, 0.3);
}

grid {
    margin: 10px;
}

grid > label {
    font-size: 12pt;
}