Not sure that it answers my question. There is something wonky going on when using the ‘max-width’ operator.
Like this?
Test
For some reason I get an error message when trying to insert an image into this thread using the image icon in Simple Post Editor quick reply box:
Firefox says:
Chrome says:
It would be helpful if you posted what you inserted. Perhaps leave off the < > delimiters so that the browser does not parse it as html.
I did not insert anything. These errors pop up the moment I try to click on the “Insert Image” icon.
See screenshot: https://i.imgur.com/XTfZ5w5.png
Perhaps you can try a different browser, or the advanced editor:
As I mentioned before, this happens in both Firefox and Chrome, only in Simple Post Editor, and only in this thread. Any other thread - it works fine. Just found it very odd.
Does anyone else get the same error when trying Simple Post Editor in this thread?
Hmmm weird. Works for me (sorry, I hate that kind of answer from admins). Anybody else can confirm or deny this?
I get exactly the same error - Firefox
Thanks for reporting.
Dunno, it works for me in Chrome and Firefox. Please try clearing the browser cache or force-refreshing the page now that I made the CSS tweak mentioned before.
Tried it. Still same problem, and it happens on multiple PCs (Windows, Linux), and my Android phone.
It’s weird that it only happens in this one thread. Odd, but no biggie.
Cleared cache same problem - firefox and Crome
Browser version maybe? 
But only in this thread? 
Latest version in both browsers
Very weird indeed. Could be an extension interfering? It’s something to do with the Javascript on that page. Or maybe somebody inserted some Javascript in one of the posts that is messing with the editor. I guess it’s not a big deal as long as it’s just that one page.
Understanding how to correctly size images is a bit of worthwhile knowledge. If seeing an image that you consider too large or small and then getting into a twist about it is just silly. Maybe not everyone knows what is considered an appropriate size to post. Older people can not see as well as teens and young adults. A large image can be helpful to us old farts. Peace.
Can understand 264. I normally use a 50 or 70% width modifier, sometimes 100% if the image resolution is big. However, there are always ways to see an image properly sized, at least outside of pages with blocking code like 
Bangbad. You can long tap or right click on images and download them, open them in a new window and or do with them whatever the browser or software you use allows to. So no big deal I think. 
Images that break the page layout are indeed annoying.
So are huge file size.
If it comes from a phone or a digital camera it is important to downsize the image before uploading it. A 1024 pixel wide image with moderate jpeg compression will be much less then a megabyte. I do it with Paint, save as same name with _1024 suffix. If i only need to show part of the image i crop it before resizing if it is still too large.
I think some picture hosting sites provide links to smaller versions of uploaded files, but i never used one, so not sure.
Huge file size is only a piece of the puzzle, it can be a burden but generally isn't for a single or a couple images. I do not usually reduce picture resolution, but I often crop them. By cropping the image you trim it down precisely removing what you don't need, while setting the meat at the forefront. :THUMBS-UP: