css height of div equivalent to page height code example

Example 1: set element equal to the size of the viewport

.container {
    height: 100vh;
    overflow: auto;
}

Example 2: css set div heigtto screen

.left {
  height: 100vh;
  width: 50%;
  background-color: grey;
  float: left;
}

.right {
  height: 100vh;
  width: 50%;
  background-color: red;
  float: right;
}