body {
    /* background: linear-gradient(125deg, red, green, blue); */
    width: 100vw;
    height: 100vh;
    overflow: hidden; 
}

canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

#collisionCanvas {
    opacity: 0;
}

  #restartBtn {
    display: none;
    position: fixed;
    top: 60%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 32px;
    padding: 15px 30px;
    cursor: pointer;
    z-index: 10;
    background-color: #e74c3c;
    border: none;
    color: white;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.3);
    transition: background-color 0.3s ease;
  }
  #restartBtn:hover {
    background-color: #c0392b;
  }