I found a rare variable?: SelectedItem , and I wonder if it is possible to set a new value for it or I should change in every place that variable is used?
/* Autofill (example: login page) focus item background */
.autocomplete-richlistitem {
&[selected] {
background-color: var(--button-hover-bgcolor) !important;
}
}
SelectedItem is just a normal(*) keyword value for color like white, black, red etc. So yes, you'll need to set it wherever it's used.
* Not entirely true, it's system color keyword and it happens that you can use prefs to set value for system colors. Go to about:config and create a new string pref ui.selecteditem and set it to #ff0000 and it should become red.