body {
    background: #d6d6d6;
}
body.fullscreen_canvas canvas {
    width: 100%;
    height: 100%;
    position: fixed;
    top: 0;
    bottom: 0;
}
body.fullscreen_canvas .canvas-wrapper {
    width: 100%;
    height: 100%;
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
}
.canvas-wrapper {
    display: block;
    width: 50%;
    padding: 0;
    margin: 0 auto;
    position: relative;
}
.canvas-wrapper canvas {
    width: 100%;
    height: 100%;
    display: block;
    margin: 0;
    padding: 0;
}
.fullscreen_btn,
.fullscreen_exit_btn {
    position: absolute;
    top: 25px;
    right: 25px;
    z-index: 50000;
    color: white;
    font-size: 2em;
}
.fullscreen_exit_btn {
    display: none;
}
body.fullscreen_canvas .fullscreen_btn {
    display: none;
}
body.fullscreen_canvas .fullscreen_exit_btn {
    display: block;
}