    * children should all have a border-box block-size that's 5px less than
     * the containing block's padding-box size in the same axis. The dimension
     * of the containing block's padding-box that we're filling will depend on
     * whether our WM is orthogonal to it or not. If we're orthogonal, our
     * expected stretch size is 46px - 5px = 41px.  If we're not orthogonal,
     * our expected stretch size is 60px - 5px = 55px. */
    margin-block-start: 2px;
    margin-block-end: 3px;

    /* We a