Hiding Excel's interface in Browser?

Question

I have an Excel sheet with a diagram, the sheet can only be opened in the browser. I want to display the diagram on a monitor and have it update automatically, which already works almost flawlessly. However, I cannot get Excel to show only the diagram, without Excel's interface. Is there any way to show only the diagram?

Thanks in advance!

Edit: I still have not found a solution and had to use a workaround (covered Excel's interface with boxes matching the background color) in the presentation program Deon.