body {
  font-family: sans-serif;
  text-align: center;
  background: #f4f4f4;
}
video {
  width: 90%;
  max-width: 400px;
  border: 3px solid #333;
  border-radius: 10px;
}
button {
  margin: 10px;
  padding: 10px 20px;
  font-size: 18px;
  cursor: pointer;
}