height property behavior

When setting the height property one would expect a value of 100% to
extend the length of the entire page but in fact it only spans the
length of the initial viewport. So, if I have a box who's content
extends beyond the initial viewport with a background-color property set
the color will stop once the user scrolls down beyond the viewport.

Is this the intended behavior of the height property with a 100% value
or is this a matter of non-compliancy? Behavior on this matter is
consistent among several browsers I tested with.