You can find default colors in this Options/Preferences window:

• Tools > Options > Content : Fonts & Colors > Colors

Note that disabling "Allow pages to choose their own colors, instead of my selections above" will affect background images.

LezLezLez said

I would like to change the highlight colour that my system applies after I have used any URL address link in the main display text. Currently it is a similar shade of blue to that of the original URL and I would like to change this to, say, red. Google tells me to edit one specific CSS file for making this change in Chrome, but I don't use Chrome!! A Windows Explorer search shows several hundred CSS files on my XP SP3 desktop running Firefox 34. Cana anyone help me please? Thanks in advance.

Thanks for your reply = this has worked for me. Regards. LezLezLez.