Why would max-width not work on this?

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;
  padding: 10px 0;
  margin: 0 auto;
  border: none;
}

The wrapper for this element:

#wrapper {
  max-width: 1024px;
  overflow: hidden;
  position: relative;
  margin: 0 auto;
  padding: 0 50px;
  text-align: center;
}

EDIT

Code added to jsfiddle: http://jsfiddle.net/BXdrG/