Somewhat accidentally, I found a way to enlarge the amount of screen space devoted to the board (at the expense of everything else).
Just use your browser's Zoom Out ( - ) feature.
Here is what it looks like in Firefox (30%) and Chrome (zoomed to 25%) which is as far as they will allow.
Firefox seems to handle it a little more gracefully, but everything seems to work in both cases.
Just don't plan on reading much in the way of chat.
To return to normal viewing, just zoom back to wherever you started from.
Click on the images to see them full size.