html, body {
    height: 100%;
    margin: 20px;    
    overflow: hidden;      
    font-family: sans-serif;
}


#toolbar {
    margin-bottom: 10px;
    position: fixed;
    top: 150px;
    left: 100px;
    right: 0;
    height: 40px;    
    z-index: 1000;
    text-align: center;
    width: 80%;
}

#toolbar button {
    font-size: 14px;     /* text size */
    padding: 8px 10px;   /* button size */
    margin-right: 10px;
}

#toolbar input {
    font-size: 18px;     /* text size */
    padding: 8px 10px;   /* button size */
    vertical-align: middle;
}

#canvasScrollArea {
    position: absolute;
    top: 200px;         
    left: 0;
    right: 0;
    bottom: 0;
    overflow: auto;
/*    overflow: hidden; */          /* changed from auto to hidden */
    -webkit-overflow-scrolling: touch; 
    text-align: center; 
}

canvas {
    border: 1px solid #333;
    touch-action: none;
    cursor: crosshair;
    height: auto;
    display: block;
    max-width: none;
    margin: 0 auto;
    max-width: 85%;
    transition: none;
/*    transform-origin: center top; */ /* zoom from top-center, not 0,0 */
}

.active {
    background: #4caf50;
    color: white;
}