You're right, the text isn't clearly visible in that area. I typically design skins with a dark theme, so the background of the theme will always contrast with the character. Therefore, if the background is dark, the tab letters will be light, making them difficult to see when placed over the character. I always aim for contrast between icons, letters, and the character, but that area of the face will always be challenging.

I always encounter this issue with other themes, but in this case, it's more noticeable due to the number of characters to represent on the screen. There are two things that can be done about it: either reduce the size of the characters' images so that a smaller area is affected or make the text of the tabs dark but not stand out as much in the rest of the bar.

Additionally, Mozilla (the developer of the skin-editing addon) has been mentioned in the addon reviews regarding the ability to add a shadow under the tab titles, but so far, this improvement hasn't been implemented in the addon.

Regarding the colors, I took them from an official image of the animation studio, and they are the ones behind them. Basically, they are the representative colors of each one.

Thank you for commenting, and I'll be thinking about what to do to improve it, at least a little. <3