* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: #0f0f0f;
  color: #fff;
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

#app {
  width: 360px;
  text-align: center;
}

h2 {
  margin-bottom: 12px;
}

#videoArea {
  display: flex;
  gap: 6px;
  margin-bottom: 14px;
}

video {
  width: 50%;
  height: 240px;
  background: #000;
  object-fit: cover;
  border-radius: 6px;
}

.controls {
  display: flex;
  gap: 10px;
}

button {
  flex: 1;
  padding: 12px;
  font-size: 16px;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

#startBtn {
  background: #1abc9c;
}

#nextBtn {
  background: #e74c3c;
  color: #fff;
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}