multicolumn summary - SquareSpace

gistfile1.html

<script type='text/javascript'>
YUI().use('node', 'event-base', function (Y) {
  Y.on('domready', function () {
    Y.all('.summary-block').each(
      function () {
        // 4 -> 3 cols
        // 3 -> 4 cols 
        // 6 -> 2 cols
       Y.all('.summary-item', this).wrap('<div class="col sqs-col-4 span-4"></div>');
       Y.all('.col > .summary-item').wrap('<div class="newSummary"></div>');
      }
    );
  });
});
</script>

<style type="text/css" style="display: none">
  .newSummary {
    margin-left: 4%;
    margin-right: 4%;
    margin-bottom: 20px;
  }
  .summary-item img {
    width: 100% !important;
    height: auto !important;
    left: 0 !important;
  }
  .summary-thumbnail {
    display: block !important;
    overflow: hidden;
  }
</style>

Inject this code snippet on the page including the Summary ( Page Settings -> Advanced -> Page Header Code Injection ).