body {
  font-family: Arial;
  text-align: center;
  background: #111;
  color: white;
}

video {
  width: 90%;
  max-width: 400px;
  border: 3px solid white;
  margin: 20px 0;
}

#resultado {
  font-size: 2em;
  margin-top: 20px;
  padding: 20px;
}

.ok {
  background: green;
}

.error {
  background: red;
}