Specify How Fonts Should Degrade

There are several default fonts that are available in all browsers. These generic font families include monospace, serif and sans-serif.

When one font isn’t available, you can tell the browser to “degrade” to another font.

For example, if you wanted an element to use the Helvetica font, but degrade to the sans-serif font when Helvetica isn’t available, you will specify it as follows:

p {
  font-family: Helvetica, sans-serif;

Generic font family names are not case-sensitive. Also, they do not need quotes because they are CSS keywords.