s://drafts.csswg.org/css-break-3/#forced-break" rel="help">

  <style>
  article
    {
      column-fill: auto; /* columns are filled sequentially */
      column-gap: 0em;
      columns: 2 100px; /* 2 columns each 100px wide */
      float: left; /* to make multi-column element shrink-wrap */
      height: 400px; /* give more than enough to go wrong */
    }

  div#yellow-normal
    {
      border-top: yellow solid 100px;
    }

  div#blue-parent
    {
      border-top: blue solid 100px;
      contain: lay