Responsive Image Sizing - Option to Disable?

[elizabeth]

Found this in another thread:

Code:

<style>
.gresponsive {
  width: 100%;
  height: auto;
}
</style>

I've got no problem with deleting that if that's all there is to it (although my guess is that this replaced some other css instruction re: image width, and if so, I'd need to replace rather than just delete). Just need a reminder on what file it's in.