There is no 12-column grid system like in other utility frameworks, however Lumo offers dynamic grid system for more complex content layouts.

Use section for a real section of content, then add class="grid" when that section should arrange its children as responsive columns.

<section class="grid">
    <article>
        First column
    </article>
    <article>
        Second column
    </article>
    <article>
        Third column
    </article>
</section>