body {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
  }

#iyzne{
    width: 50%;
    margin:0 auto;
    display:block;
}

/* PC向け（640×480） */
.game-container iframe {
  width: 640px;
  height: 480px;
}

/* スマホ向け（320×240 = 2倍） */
@media (max-width: 640px) {
  .game-container iframe {
    width: 320px;
    height: 240px;
  }

  body{
    justify-content: start;
  }
}