Vivaldi has this ages ago I also use Palemoon + Tab Kit for tab group https://addons.palemoon.org/addon/tabkit2/ https://addons.palemoon.org/addon/tabkit2/

Vivaldi has this ages ago I also use Palemoon + Tab Kit for tab group https://addons.palemoon.org/addon/tabkit2/ https://addons.palemoon.org/addon/tabkit2/ I hope Vivaldi will have colored tab groups too...