div.pushbutton {
  text-align: center;
}

button#push {
  width: 90%;
  height: 80vh;
  font-size: 1.4em;
  font-weight: bold;
  padding: 10px 30px;
  color: #fff;
  border-style: none;
  background: #00f;
  -moz-border-radius: 5px;
  -webkit-border-radius: 5px;
  border-radius: 5px;
}

button#push:hover {
  opacity: 0.8;
}

button#push:disabled {
color: #000;
background:#ff0;
}