This is happening when you open your HTML file locally because IE falls back to IE7 mode, even if the correct HTML doctype is used. If you upload the HTML to an actual web server, it should work properly.
I've now pushed a fix to GitHub. It adds this line to index.template.html:
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
This should fix IE9 and later. Note that IE8 is not supported.