body {
  border: 1px dotted black;  
}

section {
  border: 1px solid black;
  margin: 2rem;
  position: relative;
}

div {
  background: rgba(0, 0, 255, 0.5);
  border: 1px dashed black;
  height: 25px;
  margin: auto;
  width: 75px;
  top: 75px;
  left: 75px;
}

.relative {
  background: rgba(255, 0, 0, 0.5);
  position: relative;
}

.absolute {
  background: rgba(0, 255, 0, 0.5);
  position: absolute;
}

.fixed {
  background: rgba(255, 255, 0, 0.5);
  position: fixed;
}