Use your monitor controls to adjust brightness and contrast.
The long bars should be gray, yellow, cyan, green, magenta, red, and blue.
The transition from one bar to another should be sharp with no intermediary colors.

Pay special attention to the various levels of gray below the red bar.
You should see three distinct shades of gray there.
If, however, your system limits available colors, these shades of gray may not show.

The background of this page should be deep black, not dark gray.
This text should be white.

Keep your monitor free of dust and smoke.
In fact, you should clean off the dust right now, even before touching the controls.