I ran into an unusual issue over the weekend, on a simple site I put together for an annual community event. Set on a black background, access to the different pages if by clicking on graphic buttons ("About", "Events", etc.). The active page has the graphic bright and underlined, with the other buttons "dimmed" to about half opacity. Elsewhere, the linked text was a medium-to-dark green, embedded in medium gray text.
On the various LCD screens I use, this was completely visible. The linked text popped out wonderfully.