body {
    display: flex;
}

.game-container {
    width: 500px;
    height: 730px;
    position: absolute;
    left: 80px;
    overflow: hidden;
}

.border-left {
    width: 80px;
    height: 790px;
    position:  absolute;
    background-color: white;
    z-index: +2;
}

.border-right {
    width: 80px;
    height: 790px;
    position: absolute;
    background-color: white;
    z-index: +2;
    left: 580px;
}

.border-top {
    width: 660px;
    height: 50px;
    position:  absolute;
    background-color: white;
    z-index: +2;
    top: -50px;
}

.sky {
    background-image: url('fb-game-background.png');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    width: 500px;
    height: 580px;
    position: absolute;
}

.ground {
    background-image: url('bottom-background.png');
    width: 500px;
    height: 150px;
    position: absolute;
    top: 580px;
    z-index: 10;
}

.bird {
    background-image: url('flappy-bird.png');
    position: absolute;
    width: 60px;
    height: 45px;
    left: 220px;
    bottom: 100px;
    z-index: 15;
}

.obstacle {
    background-image: url('flappybird-pipe.png');
    width: 60px;
    height: 300px;
    position: absolute;
    z-index: 6;
}

.topObstacle {
    background-image: url('flappybird-pipe.png');
    transform: rotate(180deg);
    width: 60px;
    height: 300px;
    position: absolute;
    z-index: 6;
}

@keyframes slideright {
    from {
        background-position: 10000%;
    }
    to {
        background-position: 0%;
    }
  }
  
  @-webkit-keyframes slideright {
    from {
        background-position: 10000%;
    }
    to {
        background-position: 0%;
    }
  }

  .ground-container {
      height: 150px;
      width: 500px;
      left: 80px;
      position: absolute;
  }
  
  .ground-moving {
    position: absolute;
    top: 580px;
    height: 150px;
    background-image: url('bottom-background.png');
    background-repeat: repeat-x;
    -webkit-animation: slideright 100s infinite linear;
    animation: slideright 100s infinite linear;
    width: 500px;
    z-index: 10;
  }

  .score {
    position: absolute;
    top: 20px;
    left: 20px;
    font-size: 40px;
    font-weight: bold;
    color: white;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.8);
    z-index: +10;
    font-family: Arial, sans-serif;
    transition: transform 0.2s ease;
  }

  .start-instruction {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 20px 30px;
    border-radius: 15px;
    text-align: center;
    font-size: 20px;
    font-weight: bold;
    z-index: +10;
    font-family: Arial, sans-serif;
    border: 2px solid #fff;
    animation: pulse 2s infinite;
  }

  @keyframes pulse {
    0% { transform: translate(-50%, -50%) scale(1); }
    50% { transform: translate(-50%, -50%) scale(1.05); }
    100% { transform: translate(-50%, -50%) scale(1); }
  }

  .game-over {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: rgba(0, 0, 0, 0.9);
    color: white;
    padding: 30px;
    border-radius: 15px;
    text-align: center;
    font-weight: bold;
    z-index: +10;
    font-family: Arial, sans-serif;
    border: 3px solid #fff;
    box-shadow: 0 0 20px rgba(0,0,0,0.5);
    animation: gameOverFade 0.5s ease-in;
  }

  @keyframes gameOverFade {
    from { opacity: 0; transform: translate(-50%, -50%) scale(0.8); }
    to { opacity: 1; transform: translate(-50%, -50%) scale(1); }
  }