Hello,
This is a Firefox bug, see these:
https://bugzilla.mozilla.org/show_bug.cgi?id=1518863
https://bugzilla.mozilla.org/show_bug.cgi?id=1490260

Right now it affects only some PC. Also note that I've created special option in the Options page / General / "When Firefox starts, open dials page" which should help in most cases.
However the real fix needs to come from Firefox team.


Best regards,
Juraj Mäsiar

Hello,
You can override any CSS style in my add-on. See the Options page / General tab / "Custom CSS styles:".
For example, to change color of dials heading, use this:

.dials > a > div > div {
background: lightblue !important;
}

And to make group list more colorful, use this:

#groups {
background-color: rgba(255, 209, 57, 0.6) !important;
}
#groups > .selected {
background-color: orange !important;
}

You can create also new styles, just inspect the element you want to change and create new CSS rule. However make sure to pick the theme - black or while, depending on whether your final theme will be dark or light.

If you have more questions, feel free to write me to my support e-mail.


Best regards,
Juraj Mäsiar