@mixin core() {
    $border-color: var(--kbq-line-contrast-less);

    .ic-border-top {
        border-top: 1px solid $border-color;
    }

    .ic-border-bottom {
        border-bottom: 1px solid $border-color;
    }

    .ic-border-left {
        border-left: 1px solid $border-color;
    }

    .ic-border-right {
        border-right: 1px solid $border-color;
    }
}