Uh, "nested" spreads the screen out wider as the replies to comments step to the right from the one they reply to. Flat just lines them up under one another. Thats how the width tag stretches pictures out to compensate for that. Which makes my favorite pass time occur [scrolling sideways to read a thread]. it gets worse as replies to replies to replies... are added. Add pictures into those replies and, well, you see where I am going.
Photos on the site are definitely the biggest butt pain. Not all browsers act the same and not all users have the same screen size, resolution or visual acuity. Some just don't give a damn or think its funny to dump huge photos. Firefox seems quite good at making photos fit so my main photo posting mission here is file size enforcement for those stuck on slow internet. There is even one Operating System out there that uses a default picture format that can make a line drawing of your initials consume 5 megabytes of size. Very few folks customize either their OS or their browser so both factors lead to user confusion and frustration.
Maybe that settled the silt some for you. Maybe just stirred more up off the bottom.
Cheers.
TomW