#callback-dialog {
  width: min(94vw, 720px);
  height: min(90vh, 780px);
  max-width: none;
  max-height: none;
  padding: 0;
  border: 0;
  border-radius: 8px;
  box-shadow: 0 16px 50px rgba(0, 0, 0, .3);
  overflow: hidden;
}

#callback-dialog::backdrop { background: rgba(0, 0, 0, .65); }

.callback-dialog-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  font: 600 18px Arial, sans-serif;
}

.callback-dialog-close {
  border: 0;
  background: transparent;
  cursor: pointer;
  font-size: 28px;
  line-height: 1;
}

#callback-dialog iframe {
  display: block;
  width: 100%;
  height: calc(100% - 105px);
  border: 0;
}

.callback-dialog-fallback {
  margin: 8px 16px;
  font: 13px Arial, sans-serif;
}