#game-world { position: relative; width: 1000px; height: 300px; overflow: hidden; background: #fff; }
    .entity { position: absolute; }
    .platform { background-color: #800000; border-top: 4px solid #00FF00; }
    .water { background-color: #87CEEB; }
    .enemy { background-color: #90EE90; border-radius: 50%; }