div.top
{
  vertical-align:top;
  width:100%;
  border:solid 1px black;
}

div.left
{
  text-align:left;
  float:left;
  width:50%;
}

div.right
{
  text-align:left;
  float:right;
  width:50%;
}

div.bottom
{
  vertical-align:bottom;
  width:100%;
  border:solid 1px black;
}