Looks quite nice! It would be more useful if it can be integrated into Slack, Jira etc. For example a slack bot could notify people if they, or their tasks were mentioned in a meeting.
Amazing work!
I would never have imagined someone will take CSS 3D rensering this far.
Regarding scalability, my previous experiences with similar rendering techniques is that this will definitely not scale on current GPU architecture.
The problem here is that with each polygon, your GPU api performs a draw call, an expensive operation you don't want to abuse. Also, updating matrix and other uniforms with each polygon is expansive. In a certain sense, your browser has to upload your entire geometry to GPU every single frame.
I can see this approach being useful for simple scenes with relatively flat objects. For an actual 3D geometry, I would never think using this in production.