I'm currently agonizing over how light I can make various colors in my UI before I adversely affect usability. The reason for the agonizing is that different monitors have different responses. Those at work are universally poor, showing light colors as very close to white, no matter how you change the settings on the monitor itself. At home, however, I know that the same colors come through loud and clear.
One specific (albeit not brilliant) example is the color used for subtle text prompts e.g.
The majority of our UI has a white background; for relatively bold/heavy typefaces, I'm using
#E7E7E7 as the text color, and darkening it to
#CCCCCC for smaller font-sizes and lighter typefaces. I desperately don't want to make the messages so dark that they dominate the screen or demand unnecessary levels of attention, but neither do I want them to be so faint that you can barely read or even notice them.
How do you design for subtlety while allowing for different color responses in users' monitors? Do you use a rule of thumb to decide what's the lightest legible text color on, say, a white background?
I'd be interested to hear any advice.