https://developer.mozilla.org/en-US/docs/Web/CSS/columns
https://developer.mozilla.org/en-US/docs/Web/CSS/column-gap
In the gridder, right click on the element and choose "set html class and id". For "html class" enter:
mycolumns
Enter the custom css in "lay options" -> "custom css & html".
.mycolumns{ columns: 2; column-gap: 20px; }