Switch from interpolated margins to CSS columns

[Flarp]

As of now, interpolated margins are used to put everything in a column. This is no good, CSS columns should be used instead. It would make the code so much nicer.

Distri.js/distri.js

Line 169 in db79253

return `<div style="width: 200px; height: 300px; position: absolute; left: ${200 * (ind % 3)}px; top: ${300 * Math.floor(ind / 3)}px; display: inline-block" id="distri-item-${ind}">