New update!
I've just updated the site with a swath of changes that I've been working on for a few weeks! Here's a rundown of all the updates:
copy permalink: create a link to the shape you're working on that will take your pals directly to an exact copy of what you're looking at, regardless of whether you're on desktop or mobile, including any highlighted cells! This also lets you save your progress if you need to close the window and come back later.
local storage: your browser will automatically remember the shape you're working on, along with any highlighted cells, and will return you to that point next time you visit the site.
highlighting improvements: you can now right click and drag to highlight many cells in one gesture, and erase the highlights in the same way but starting on a highlighted cell.
fullscreen mode: new button in the bottom right to make the diagram fill your whole display.
crosshairs now centre on a cell for better clarity
diagram has a watermark to help people find the site
The next update will either feature more curvy shapes, or something in another dimension. What would you vote for?