This is a fixed distance, but is relative to the current font size, so it scales nicely. Only use absolute length units when the physical characteristics of the output medium are known. Always specify a fallback generic font. Use numbers, not names, for colors. Be sure to validate that your pages are still readable without style sheets.
Some examples follow.
Use relative length units and percentages. Only use absolute length units when the physical characteristics of the output medium are known. Content developers should use style sheets to style text rather than representing text in images. Using style sheets will also allow users to override author styles and change colors or fonts sizes more easily. Text without spaces will be transformed more effectively to speech.