Why would max-width not work on this?

Question

Using plain old CSS, why won\'t \'max-width\' not work on the following:

button {
  text-align: center;
  max-width: 540px;
  height: auto;
  display: block;
  p         


        

Answer 1

button {
  text-align: center;
  max-width: 540px;
  height: auto;
  display: block;
  padding: 10px 0;
  margin: 0 auto;
  border: none;

  width:100%; /* you forgot this */
}