Grouped buttons are not displayed correctly if some of them are hidden

[NikitOS]

Affected version

Any

To be clear, in XenForo out of the box there are no problems with this, since the only use case is grouping always visible buttons:

But I needed to hide some buttons by default and display them via JS. And there is a problem: if the first or last button is hidden, the next or previous ones will have non-rounded borders:

Spoiler: Possible fix

To get around this problem, I wrote the following LESS:

.fixedButtonGroup
{
    display: inline-block;
    vertical-align: top;
    .m-clearFix();

    &.buttonGroup--aligned
    {
        vertical-align: middle;
    }

    > .button
    {
        float: left;

        &:not(.is-hidden)
        {
            ~ .button,
            ~ .buttonGroup-buttonWrapper > .button
            {
                border-left: none;
                .m-borderLeftRadius(0);
            }
        }

        &:has(~ .button:not(.is-hidden)),
        &:has(~ .buttonGroup-buttonWrapper > .button:not(.is-hidden))
        {
            .m-borderRightRadius(0);
        }
    }

    > .buttonGroup-buttonWrapper
    {
        float: left;

        &:has(.button:not(.is-hidden))
        {
            ~ .button,
            ~ .buttonGroup-buttonWrapper > .button
            {
                border-left: none;
                .m-borderLeftRadius(0);
            }
        }

        &:has(~ .button:not(.is-hidden)) > .button,
        &:has(~ .buttonGroup-buttonWrapper > .button:not(.is-hidden)) > .button
        {
            .m-borderRightRadius(0);
        }
    }
}

There may be a better solution, but I'm not a CSS developer.