body, html {
    height: 100%;
    margin: 0;
    padding: 0;
    background-color: #f8f8f8;
    overflow: hidden;
}

#canvas {
    display: block;
    width: 100vw;
    height: 100vh;
    cursor: pointer;
}

#savePngBtn {
    position: fixed;
    top: 20px;
    left: 20px;
    background: rgba(255, 255, 255, 0.9);
    color: #333;
    border: 2px solid #333;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    font-weight: bold;
    transition: all 0.2s ease;
    z-index: 1000;
}

#savePngBtn:hover {
    background: #333;
    color: white;
    transform: scale(1.05);
}

#savePngBtn:active {
    transform: scale(0.95);
}