.popover {
    background-color: #212121;
    color: $transparent_white;
}

<div class="popover bs-tether-element show bs-tether-element-attached-top bs-tether-element-attached-center bs-tether-target-attached-bottom bs-tether-target-attached-center" style="top: 0px; left: 0px; position: absolute; transform: translateX(243px) translateY(294px) translateZ(0px);">
    <div data-reactroot="" class="popover-inner">
        <div class="component-rate-popover popover-content">
        </div>
    </div>
</div>

.popover.popover-bottom::after,
.popover.bs-tether-element-attached-top::after{ border-bottom-color:#212121; }

.bs-popover-bottom .arrow::after, .bs-popover-auto[x-placement^="bottom"] .arrow::after {
        top: 1px;
        border-bottom-color: #212121;
}