Very good addon with possibility to hide your tabs that is good in tab-management, beatiful UI, but multi-panel doesn't work properly. Sometimes tabs dissapear from a certain panel, hope you will fix it.

p.s. Is it possible to change ONLY group icon color?
In example, "favicon-placeholder-bg" selector does not fit to this case very well, because it changes other icons aswell, but in order to visually separate tabs this thing could be very useful

p.s.s. Found solution if someone needs. Place it in Style edit.

.Tab[data-parent] .fav .placeholder > svg {
fill: red;
}

But it changes all your data-parent tabs, remember this.

If you need to change color/text-align of your groups in tab panel, try this:

.Tab[data-parent] .title {
color: black;
text-align: center;
}