* {
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}
html, body {
    width: 100%;
    height: 100%;
}
body {
    padding:0;
    margin:0;
    overflow:hidden;
	height: 100vh;
}
canvas {
    padding:0;
    margin:0;
}
div.btnbg {
    position:fixed;
    left:0;
    top:0;
}
footer {
    position: fixed;
    width: 100%;
    height: 40px;
    line-height: 40px;
    z-index: 2;
    color: #ffffff8f;
    font-size: 10px;
    left: 0;
    bottom: 0;
    text-align: center;
    font-family: monospace;
}