It is really weird. A good example is thread https://forums.macrumors.com/threads/1886408/. Pictures:
img[src*="bar"] {
height: 10px !important;
}
It's a file containing customisations to CSS styles. Copy the text above into a new file, save it somewhere with a .css extension, and set it up in Safari > Preferences > Advanced.
#mainContainer .tborder img[height="10"]{
height: 10px !important;
}
I wrote something to add to your user stylesheet* which sort of fixes it:
Code:img[src*="bar"] { height: 10px !important; }
I find this fix works better:
Code:#mainContainer .tborder img[height="10"]{ height: 10px !important; }
The "#mainContainer .tborder " part isn't needed, but I put it there just to minimize the chance of conflict with other websites.