Block and inline areas are created by particular elements in the
formatting objects document. Line and glyph areas are created by the
formatter as necessary. For the most part, the rendering engine
decides exactly where to place the boxes and how big to make them,
based on their contents. However, you can specify properties for
these boxes that adjust both their relative and absolute position,
spacing, and size on a page. Most of the time the individual boxes
don't overlap. However, they can be forced to do so
by setting the properties absolute-position,
left, top,
right, and top on the boxes.