Change inactive selection color in Firefox
No, you can't
Not on Firefox at least.
Reason I'm answering with a no, is to save both of your time and others who might try to find some solutions / hacks.
Since you already know about the css specification. I might want to add that,
Remember Firefox has it's own version of
::selection
,::-moz-selection
. It also has it's own version of:window-inactive
,:-moz-window-inactive
. Unfortunately using these things together doesn't work.Source: CSS Tricks
/* Does work */
::-moz-selection {
background: rgba(255,0,0,0.9);
color: white;
}
/* Doesn't work */
::-moz-selection:-moz-window-inactive {
background: rgba(255,0,0,0.3);
}
/* Nor this */
:-moz-window-inactive::-moz-selection {
background: rgba(255,0,0,0.3);
}
Also, Bugzilla has years old bugs requesting this feature and talking about it's inability to handle inactive selections but no responses on those. Here is a list. Some of them are even 11 years old. I am planning to talk to someone about this and report a new bug myself with some more details, might add their response or the bug number here so that you can get updates.
So, for now I think you shouldn't be looking for some hacks, it'll only waste your time.
Thanks
Update: here is the bug to keep an eye on bugzilla, lets see what the dev team has to say.