body {
  min-height: 100vh;
}

.preview-video,
.student-video,
.modal-video {
  width: 100%;
  background: #111;
  border-radius: 16px;
  display: block;
}

.preview-video {
  aspect-ratio: 16 / 9;
  object-fit: contain;
}

.student-video {
  aspect-ratio: 16 / 9;
  object-fit: contain;
  cursor: pointer;
}

.modal-video {
  aspect-ratio: 16 / 9;
  object-fit: contain;
  border-radius: 0;
}

.screen-card {
  transition: transform .15s ease, box-shadow .15s ease;
}

.screen-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 .75rem 1.5rem rgba(0,0,0,.12);
}

.empty-state {
  padding: 60px 20px;
  text-align: center;
  color: #6c757d;
}