firebug says text color is dark blue, color on screen is white. Why?

[Dan Allen]

This page shows the problem.
https://www.hollyswritingclasses.com/zdevDanAllen/firbug_bug.html

If you mouse over the links to the downloads, the background changes to white.  The color is supposed to be dark blue.  Firebug says it is dark blue.  Actual color is white and readable.

UNREADABLE TEXT:  FIREBUG REPORTS WRONG COLOR FOR TEXT.

[Sebastian Zartner]

When I hover the buttons using Firefox 44.0.2 + Firebug 2.0.14 on Windows 7 I see the text in dark blue. Note that the actual rule making the text blue is .btn.btn-blue:hover, not .btn.btn-blue::after.
If you didn't change anything in that page in the meantime, which fixes the issue, I suggest you create a new Firefox profile and try out there. If the text is blue there, it must be some setting or extension that causes the text to be white.

Some more steps to track the issue down are available within the first aid guide for Firebug.

Sebastian