浮動ボックスの重ね合わせ

<div id="abs1"><strong>DIV #1</strong><br />position: absolute;</div>
<div id="flo1"><strong>DIV #2</strong><br />float: left;</div>
<div id="flo2"><strong>DIV #3</strong><br />float: right;</div>
<br />
<div id="sta1"><strong>DIV #4</strong><br />no positioning</div>
<div id="abs2"><strong>DIV #5</strong><br />position: absolute;</div>
<div id="rel1"><strong>DIV #6</strong><br />position: relative;</div>

div {
  padding: 10px;
  text-align: center;
}
strong {
  font-family: sans-serif;
}
#abs1 {
  position: absolute;
  width: 150px;
  height: 200px;
  top: 10px;
  right: 140px;
  border: 1px dashed #900;
  background-color: #fdd;
}
#sta1 {
  height: 100px;
  border: 1px dashed #996;
  background-color: #ffc;
  margin: 0px 10px 0px 10px;
  text-align: left;
}
#flo1 {
  margin: 0px 10px 0px 20px;
  float: left;
  width: 150px;
  height: 200px;
  border: 1px dashed #090;
  background-color: #cfc;
}
#flo2 {
  margin: 0px 20px 0px 10px;
  float: right;
  width: 150px;
  height: 200px;
  border: 1px dashed #090;
  background-color: #cfc;
}
#abs2 {
  position: absolute;
  width: 150px;
  height: 100px;
  top: 80px;
  left: 100px;
  border: 1px dashed #990;
  background-color: #fdd;
}
#rel1 {
  position: relative;
  border: 1px dashed #996;
  background-color: #cff;
  margin: 0px 10px 0px 10px;
  text-align: left;
}