如何使用 CSS 设置 row-col 布局中的默认间距？

<footer id="footer">
    <div class="rxc-wrap el-page-container bg-dark text-light">
        <div class="container py-5">
            <div class="row">
                <div class="col-12 col-lg-3">
                    <h4 class="el-title font-weight-normal mb-3 pb-2">about</h4>
                    <ul class="list-unstyled mb-0 d-flex flex-column" style="gap: .5rem">
                        <li>
                            <a href="?part=about-headmaster" class="text-light">headmaster</a>
                        </li>
                        <li>
                            <a href="?part=about-our-values" class="text-light">our values</a>
                        </li>
                        <li>
                            <a href="?part=about-history" class="text-light">history</a>
                        </li>
                    </ul>
                </div>
            </div>
        </div>
    </div>
</footer>

div.row {
    row-gap: 2rem;
}