Q:

http://sigmajs.org/ les mis tutorial - why are my canvases 0 height? 

I'm working through the http://sigmajs.org/ les miserable tutorial.  I'm curious, when I run a local server and view my index.html page, why are the canvases generated by sigmas.js 0 height?  

https://github.com/micahstubbs/les-mis-tut/blob/master/02/index.html

A:

Because your CSS code is false. 
Replace it with this :
 #sigma-container {
  position :absolute;
  width :500px;
  height :500px;
  }

