body {
  margin: 0;
  background: black;
  color: white;
  font-family: Arial;
}

.center {
  position: absolute;
  top:50%;
  left:50%;
  transform:translate(-50%,-50%);
  text-align:center;
}

.btn {
  display:inline-block;
  margin-top:20px;
  padding:12px 20px;
  border:1px solid red;
  color:white;
  text-decoration:none;
  cursor:pointer;
  background:transparent;
}

.sub {
  color:#888;
}

.terminal {
  padding:20px;
}