Chalkboard does not work when width and height are set

[clayms]

When I include the following in the YAML header of my markdown file:

width: \"100%\"
height: \"70%\"

The following issues occur:

1. The chalkboard grid will not display,
2. I cannot draw on the chalkboard.

If I comment out those two lines in the YAML header, all functionality is restored.

[Asvin Goel]

Duplicate of #104