This diagram illustrates the four areas of the generic
CSS box: content, padding, border, and margin.
There are four nested boxes: the content area
is the innermost, then padding, border,
and margin areas. Each area has a different border style to
distinguish its edge: the content edge is thin and solid; padding is
thin and dashed; border is thick and solid; margin is thick
and dashed.
Below the boxes, a legend lists the border styles used for
the four edges.
