Coloured in the grid, so it differs from your average squared paper–can't do that by hand every second
based of my initial sketch/block: d3 | simple square grid
Modified http://d3js.org/d3.v3.min.js to a secure url
https://d3js.org/d3.v3.min.js
https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.min.js