ampersand css

1.class {
2    margin:20px;
3    &:hover {
4        color:yellow;
5    }
6}
7

1//there is a lot of repetition
2.button:visited {
3  //style goes here
4}
5.button:hover {
6  //style goes here
7}
8button:active {
9  //style goes here
10}
11//this can be simplified by using an ampersand
12.button {
13  &:visited { }
14  &:hover { }
15  &:active { }
16}