Got this notification when I opened Chrome when coming back to my desk after lunch.
“We changed our privacy settings to allow us to snoop on what you’re looking at and shove you ads accordingly. Feel free to opt out, but we’ll probably opt you back in when you aren’t paying attention.”
Besides just jumping ship to veritcal tabs, I’d be shocked if there wasn’t a user .css customization, settings option, or other small extension to get that in Firefox.