css实现空心三角形

<div class="triangle"></div>
.triangle {
        width: 0;
        height: 0;
        border-style:solid;
        border-width: 0 8px 15px;
        border-color: transparent transparent #568CFC;
        position: relative;
}

.triangle::before {
        content: '';
        border-style: solid;
        border-width: 0 8px 15px;
        border-color: transparent transparent white;
        position: absolute;
        top: 1px;
        left: -8px;
}