Ultimately this comes down to a little css as HaxO’s answer suggests.
I just edited the .html file that was produced after building to get what you were requesting…
in the .wrapper make sure you have the two following values { min-height: 100%; min-width: 100%; }
Then in the #canvas:not([fullscreen]) make sure to set { width: 100%; }
If something isn’t correct, try to be a little more descriptive than “it doesn’t work” so we can try to address it accordingly.