title: how to span multiple columns in a multi-column linkki section
body: <p>What is the best way to create a multi-column layout in <a href="https://github.com/linkki-framework/linkki" rel="nofollow noreferrer"><strong>linkki</strong></a> with a field spanning multiple columns?</p>
  <pre><code>| Label1: Field1(quite long)       |
  | Label2: Field2 | Label3: Field3 |
  </code></pre>
  <ol>
  <li>CustomLayoutSection - I would like to avoid that for such a simple(?) case</li>
  <li>SectionLayout.COLUMN, add a blank Label after Label1, use CSS to make Field1 cover it (how?)</li>
  <li>maybe add some kind of colSpan-aspect?</li>
  <li>Use multiple Sections - I'd like to avoid that</li>
  </ol>