html, body {
      height: 100%;
      margin: 0;
      display: flex;
      justify-content: center;
      align-items: center;
      background-color: #1e1e1e;
      overflow: hidden;
    }

    .game-container {
      display: flex;
      align-items: center;
    }

    canvas#game {
      background-color: #0d1a2b;
      border: 5px solid #ffffff;
      display: block;
    }

    .scoreboard {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background-color: #09121b;
      color: white;
      font-family: sans-serif;
      font-size: 18px;
      display: flex;
      justify-content: space-around;
      padding: 10px 0;
      z-index: 1000;
    }

    .popup, .game-over-popup {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      display: flex;
      justify-content: center;
      align-items: center;
      background-color: rgba(0, 0, 0, 0.7);
      z-index: 10;
      color: white;
      font-family: sans-serif;
      text-align: center;
    }

    .popup .content, .game-over-popup .content {
      background-color: #0d1a2b;
      padding: 20px;
      border-radius: 10px;
      box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
    }

    .popup .content button, .game-over-popup .content button {
      margin-top: 20px;
      padding: 10px 20px;
      font-size: 18px;
      background-color: #ffffff;
      border: none;
      cursor: pointer;
      border-radius: 5px;
    }

    .game-over-popup, .speed-up-alert {
      display: none;
    }

    .speed-up-alert {
      position: fixed;
      top: 40%;
      left: 50%;
      transform: translate(-50%, -50%);
      color: yellow;
      font-size: 24px;
      padding: 10px;
      border-radius: 5px;
      z-index: 999;
    }

    @media (max-width: 768px) {
      .game-container {
        flex-direction: column;
      }

      canvas#game {
        width: 90vw;
        height: auto;
      }
    }