Template:Mbox/styles.css

td.mbox-imageright {             /* The right image cell */
    border: none;
    padding: 2px 0.9em 2px 0;    /* 0px left, 0.9em right */
    text-align: center;
}
td.mbox-empty-cell {         /* An empty narrow cell */
    border: none;
    padding: 0;
    width: 1px;
}