.canvas-container {
    /* This container's width is determined by the WordPress theme's content column. */
    /* It serves as the boundary for our width calculation. */
    width: 100%;
}

#panelClockCanvas {
    /*
     * display: block and margin: 0 auto are essential for centering.
     * The actual width/height will be set by JavaScript.
     * This CSS does NOT try to size the canvas.
    */
    display: block;
    margin: 0 auto;
}