css change text size

1.class {
2	font-size: 12px;
3}

1p {
2	font-size: 150% /*px, cm, in, etc.*/; 
3}

1font-size: 2em;

1.class{
2  	font-size: 100%;
3}
4
5.class{
6  	font-size: 20em;
7}
8
9.class{
10  	font-size: 20px;
11}
12
13.class{
14  	font-size: 20pt:
15}

1// to scale font size in relation to its parent element
2style="font-size: 2vw;"