向上箭头

<span class="open-icon-up"></span>

<style>
.open-icon-up {
    display: inline-block;
    position: relative;
    width: 14px;
    height: 14px;
    cursor: pointer;
}

.open-icon-up::before {
    content: '';
    position: absolute;
    top: 6px;
    left: 3px;
    width: 8px;
    height: 8px;
    border-left: 1px solid var(--color-font-2);
    border-top: 1px solid var(--color-font-2);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
    transition: all .5s;
}

.open-icon-up:hover::before {
    border-left: 1px solid var(--app-color-2);
    border-top: 1px solid var(--app-color-2);
}
</style>