[Request] More fine-tuned customization

[bqback]

I think it would be nice to also add options for

• text color for the label content (tab name) and counter -- currently this add-on only covers background colors of the CSS, and TST itself has functionality to set both of these colors. I'd like to be able to use dark background and light backgrounds without sacrificing text visibility on one of the background types by setting a text color that fits the other
• explicit setting of values for hover and active states, either as an absolute value for all tabs, or per-domain like the general background -- this one actually came from a bug I encountered with one specific color's brightness in active and hover states being lower than the default state value despite both settings only affecting saturation and keeping the brightness at 100% of the default value.