vis-saturday and vis-sunday classes (gray weekend days) overflow on the first of the month

[ge0ffrey]

Using this style:

    <style>
        .vis-time-axis .vis-grid.vis-saturday,
        .vis-time-axis .vis-grid.vis-sunday {
            background: #D3D7CFFF;
        }
    </style>

shows a bit too much gray on the first of any month:

vis-timeline 7.4.9 on Chrome.