Why is my text not black on Ubuntu 16.04?

So I'm using firefox and it looks like the blacks aren't really black on my monitor.

I did a screenshot and put it into gimp and it tells me that it's 54/54/54 not 0/0/0 for black.

No wonder text doesn't look dark like black should be.

The top text has been darkened by me in gimp to 0/0/0. The bottom text is 54/54/54.

This has been zoomed up by 500%.




Actual size: