body {
 font-size: medium;
  }
small {
 font-size: smaller;
 }
big {
 font-size: larger;
 }
h1 {
 font-size: xx-large;
 }
h2 {
 font-size: x-large;
 }
h3 {
 font-size: large;
 }
h4 {
 font-size: medium;
 }
h5 {
 font-size: small;
 }
h6 {
 font-size: xx-small;
 }