I managed to solve it with your help, I applied the following:
I tried left: -9999px, but this expands the vertical scrollbar in IE... I also wrapped my textarea in another DIV and applied the visible/invisible styles to that, because the textarea would lose its scroll position otherwise. I tested this in Chrome, Firefox, IE and Safari on my iPhone. Just a note, the DIV wrapped around the textarea didn't seem to help in FF, and the scrollbar still reset. But the scrollable DIVs are fine now. Thanks for your help!