* {
  box-sizing: border-box;
}

body {
  margin: 0;
}

.board {
  width: 100%;
  max-width: 680px;
  aspect-ratio: 1 / 1;
  min-height: 280px;
}

.stream-wrap {
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
}

.stream-wrap iframe {
  width: 100%;
  height: 100%;
  border: 0;
}

.view-panel.hidden {
  display: none;
}

@media (max-width: 640px) {
  .board {
    min-height: 220px;
  }
}