title: Getting divs to fill all available space, 3 columns, fixed widths, variable heights
body: <p>The best way to explain this is with the below image. You can see I have 3 divs floated left with a fixed width but variable height. </p>
  
  <p><strong>When I add a 4th I would like it to slot underneath the 2nd div because there is space available.</strong> </p>
  
  <p>I would like all following divs to use the space as efficiently as possible, slotting in where they can.</p>
  
  <p>I saw a jQuery plugin achieve this once, but I don't know what the technique is called so I cannot find it!</p>
  
  <p><img src="https://i.stack.imgur.com/LFzM9.png" alt="example"></p>
  
  <p>Thank you.</p>