how to remove whitespace below my footer in html

1body {
2  margin: 0px;
3  font-family: Arial;
4  line-height: 20px;
5}
6#header {
7  height: 20px;
8  background: #222;
9  color: white;
10}
11#content {
12  min-height: calc(100vh - 40px); substract 40px since 20 are from header and 20 from footer
13}
14#footer {
15  height: 20px;
16  background: #222;
17  color: white;
18}