CSS position

<div class="relative">
    Relative
    <div class="absolute top">Absolute to parent</div>
    <div class="absolute right bottom">Absolute to parent</div>
</div>
<div class="absolute right free">Absolute to document</div>
<div class="fixed right top">Fixed to viewport</div>
<div class="fixed right bottom">Fixed to viewport</div>

div {
  padding: 1rem;
  margin: 1rem;
  border-radius: 1rem;
  width: 50vw;
  background-color: lightgrey;
}
.relative {
  position: relative;
  height: 150vh;
}
.absolute {
  position: absolute;
  background-color: blue;
}
.fixed {
  position: fixed;
  background-color: springgreen;
}
.left {
  left: 1rem;
}
.right {
  right: 1rem;
  text-align: right;
}
.top {
  top: 2rem;
}
.bottom {
  bottom: 2rem;
}
.free {
  top: 10rem;
  background-color: yellow;
}
.relative .absolute {
  color: white;
}