2 Divs Side-by-side Causing Me Grief

I wanted to just use standard INPUT buttons and colourise them, but user's
of my web app want to continue creating their own buttons and using these in
css. Before I used straightforward images, but creating an image for each
button was a mare. You see this is all to do with giving people the ability
to change the look of the web app, in other words a skin, using nothing more
than pics and css files.

My theory was that I create a div, span or whatever for the left hand side
of the button and ref the image (in css) to be a 2px wide img that can have
the curved left hand edge of the button.

I would then put a div, span or whatever next to this and the reference
image would be a really long image (horizontally speaking) so that if the
button text was long then this would keep moving to the right and
accommodate basically any text length. Code: