#page {
  max-width: 800px;
}

@media screen and (max-width: 600px) {
  input.form-control, select.form-control {
    padding: 0.2em;
  }
  .input-group-text {
    padding-left: 0.1em;
    padding-right: 0.1em;
  }
}

#sourceVideoGraphical {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #EEE;
}

#sourceVideoGraphical>div {
  background: #e0a800;
  font-size: 2em;
}

.btn-narrow {
  padding-left: .2em;
  padding-right: .2em;
}