Is it possible to have 100% width?

[corrspt]

I've tried to use FCBKComplete (Great plugin by the way) and the width to 100% (instead of using a static hardcoded value). But havent had much luck. I tried messing with the CSS but when I set a percentage value the input gets very tiny (and it's irrelevant which value (10, 50 or 100%) I put there, only when I use 100px, 500px the component respects the value.

Thanks