body {
  background: #101820;
  color: #fff;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  text-align: center;
}
.key-box {
  margin: 3em auto 2em auto;
  padding: 1em 2em;
  background: #fff;
  color: #101820;
  font-size: 2.5em;
  border-radius: 12px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.2);
  display: inline-block;
}
video {
  margin-top: 2em;
  border-radius: 8px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.3);
}