        height: 100%;
            width: 100%;
        }

        /* Make canvas fill entire document: */
        canvas {
            margin-right: auto;
            margin-left: auto;
            display: block;
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
        }

        .centered {
            margin-right: auto;
            margin-left: auto;
            display: block;
            position: absolute;
            top: 50%