I'm not sure how feasible this is, but I don't usually operate in maximized windows. When someone posts a large image (by pixels), I have to right-scroll until the image ages off the screen.

Thanks!
This message was last updated by the user at 14:18, Sat 28 May 2016.

OMG this is so needed!

At least for us mobile users.

Of course, more options on handling width in total would be nice. I hate scrolling from side to side when zoomed in enough to read because the text is too small when the width fits the screen. Pictures make this so much worse.

Having a spoiler tag that hid the contents behind a button would be a solution as well, no?

Good idea as a work-around. But resizing gracefully would still be valuable.

Not really.  The way RPoL handles spoilers is to convert the text to the exact same colour as the background so that it can't be seen.  It's done that way so that it doesn't require javascript (not every browser plays nicely with js).  Unfortunately it means that the spoilers can't hide images.  Or recoloured text.