CSS percentage question

Relates to http://stackoverflow.com/questions/12019662/what-does-percentage-mean-in-the-following-most-trivial-html

by mark69_fnd

HTML

<!DOCTYPE html>
<html>
<head>
<style type="text/css">
#container 
{
  border: 1px solid red;
}
body
{
  outline: green solid 1px;
}
p.bottommargin 
{
  outline: green solid 1px;
  margin-bottom:1%;
}
</style>
</head>
<body>

<p>This is a paragraph with no margin specified.</p>
<div id="container">
<p class="bottommargin">This is a paragraph with a specified bottom margin.</p>
</div>
<p>This is a paragraph with no margin specified.</p>

</body>
</html>