transparent

The transparent value makes something transparent. (It’s the same as opacity: 0.)

Example

This paragraph has a transparent background

This paragraph has a transparent foreground

All paragraphs on this page have a background-color: #eeeeee. Here are the full styles; I added a selection style to make sure you can see the transparent text when you select it:

p {
	background-color: #eeeeee;
}

.test-bg {
	background-color: transparent;
}

.test-fg {
	color: transparent;
}

::selection {
	color: black;
	background-color: #dddddd;
}

::-moz-selection {
	color: black;
	background-color: #dddddd;
}