That does not sound like the default fonts, unless it is picking up something from your theme in Windows 10. Tried changing it?

i wondered about that, too, but when i changed the theme, the task list on the calendar tab remained light green. nothing i do seems to affect that list. i was hoping i was missing a setting somewhere.

I don't use the task list in Thunderbird so forgive me if this suggestion doesn't help. I'm wondering if the light green colour indicates the status of the task? Does it mean (for example) task due? Does the font colour change if the task is overdue? If so I can't think how you could change it because it's built in to Thunderbird. There is however an add-on called Chromatasks. This allows you to change the background colour of the row on which the task is displayed. The idea seems to be that you can set the background to the colour of the calendar to which the tasks belong. So suppose (for example) that you currently have a calendar displayed in Thunderbird which you call 'appointments', and in it you have all your normal calendar events - meetings, appointments etc. You could then create an additional calendar called 'tasks' and put into that only your tasks and to-dos. You could set it so that it doesn't display in the daily/weekly/monthly view, so the tasks wouldn't clutter up the display of your appointments. If you then set the colour of your 'tasks' calendar to (say) dark grey, and install the add-on, all your due tasks should be visible as light green text on a dark grey background. That isn't exactly what you want, I know, but it might help? Just a thought anyway.

thanks for your thoughts. while it didn't solve the problem, it did educate me. you're right. tasks not done are light green. when you check mark the task as done, it does change to black.....but with a strike through it. bottom line is that i can't get there from here, but at least i know that now.

> Options > Calendar >general there is an option to optimize colors for accessibility. As red green is the most common form of color blindness. That setting will almost certainly change the color to something else. perhaps black.