Hi @prowriter, happy to see you're using the Simple Razoo Donations plugin.
It looks like the issue you're dealing with stems from the fact that the Twenty Eleven theme is responsive. Basically, the way it works is when the browser window is no smaller than 800 pixels wide the sidebar takes up 30% of the entire website's width. Since the Razoo donation form is 300 pixels wide, anytime the sidebar shrinks to less than that some of it is going to get cut off.
For example, if the browser window width is 850 pixels wide the sidebar is only going to be 255 pixels wide (850 pixels x 30% = 255 pixels), which isn't big enough for the donation form.
To fix this you may need to adjust the #secondary style on line 30 of style.css. Right now it reads:
If you adjust the width to be 38% or greater the box should never be cut off. I will say that this may have unwanted affects on the rest of the layout, so please check the rest of the theme after making a change.
I hope that's helpful.
Jonathan, Wired Impact