Do “Web-safe colors” matter?
Not really, not in this case. Although these help describe how a browser will set the computer’s palette at a depth of “hundreds of colors”, these color-cube values can still shift on a monitor set to “thousands of colors”. The Web-safe color discussions are a bit different than these 16-bit rounding discussions. To summarize, a monitor set to display “thousands of colors” can only show a fraction of those seen on other monitors, and different renderers inside a browser may round colors in different ways.