title: html layout: how to float divs vertically
body: <p>How do I get divs to float vertically like in this picture:</p>
  
  <p><img src="https://i.stack.imgur.com/z0b3Y.png" alt="enter image description here"></p>
  
  <p>Background: I have a grid of checkboxes with content sorted alphabetically and I'd like to have alphabetic order progress vertically (since horizontal order is quite hard to follow). All the divs have same size (width like picture, height = 1 line size).</p>
  
  <p><strong>Update:</strong> To clarify: The main intention is to have a table layout with a variable amount of columns based on available screen width and have the cells in <em>column-major</em> order. The actual number of divs is not known in advance.</p>