Originally Posted by meme
one of the reasons that Sigil doesn't have a Book View button to change the foreground or background colour of the text is first because no one has asked for it. Mostly because most books are not in colour, and coloured text may not show up well on most of the greyscale readers.
A whole LOT of people will be getting an inexpensive tablet computer for Christmas. I think we're going to have to start taking colour content in our eBooks a lot more seriously next year.