difficult aligning codemirror textarea with other textarea

I have html with two textareas - one is bound to the codemirror the other is a simple textarea. I am trying to get them to align with each other vertically. The codemirror is above the other on the form and I can’t seem to get the right hand edges to line up reliably. Fussing with the width of the simple text area I can get there with percentages but when I resize the window larger or smaller it is miss-aligned again. Is this a known issue with a resolution? I can put together a fiddle if this write-up is not clear.

wasn’t a codemirror problem - Just a textarea styling issue. I’m a bitt of a noob but I found trying to create the fiddle led me to the answer I needed.

This fiddle http://jsfiddle.net/TcqAf/84/ both displays and answers the problem. Seems that Codemirror did the boxsizing for their textarea - I needed to add it to mine.