card 左箭头

<style>
@media (min-width:768px) {
.card .card-caret::after, .card .card-caret::before{position: absolute;top: 11px;right: 100%;left: -8px;display: block;width:8px;height: 16px;pointer-events: none;content: " ";-webkit-clip-path: polygon(0 50%, 100% 0, 100% 100%);clip-path: polygon(0 50%, 100% 0, 100% 100%);}
.card .card-caret::after {margin-left:1.5px;background-color:rgb(247, 247, 247);}
.card .card-caret::before{background-color:var(--bs-card-border-color);}
}
.card-timeline .card::before {position: absolute;top:-1.55rem;bottom: 0;left:1.55rem;display: block;width: 2px;height:1.55rem;content: "";background-color:var(--bs-card-border-color);
}
</style>