css set div heigtto screen

1div {
2    height: 100vh;
3}

1body, html {
2  height: 100%;
3}
4
5#right {
6  height: 100%;
7}

1.left {
2  height: 100vh;
3  width: 50%;
4  background-color: grey;
5  float: left;
6}
7
8.right {
9  height: 100vh;
10  width: 50%;
11  background-color: red;
12  float: right;
13}