Firefox is displaying pages incorrectly, spreading portions of content horizontally, while the rest of the page is okay. E.g- Amazon's header is stretched, with spaces between letters & words. Google results headings spread. Wells Fargo has problems too.

Question

I am using Safari to send this question, as I am upset by in Firefox on many sites, where the horizontal spacing is busted. e.g.:
My display is 1920x1200 but still not wide enough to show the whole site horizontally in these sites! In addition, the text is all over the place.
At https://www.wellsfargo.com/biz/ for example, it is as if Firefox is not reading the css for the text, some of which is in narrow columns and some scattered!
Amazon.com, -- the header at the top is so wide I have to scroll to see it and many of the words have huge gaps between letters. In the home page body, most of it is okay, but down the right some items have prices that look like this: $56. 3 8
At Google, the linked heading of the results are stretched out horizontally.... not all, but on some searches it was prevalent.
What on earth is going on? I think I am going to try to get back an earlier version from my backup and reinstall that for the meantime... this is really a drag.
I put amazon in the url below, but note the examples above too.

Answer 1

Thanks anyway, but neither of these suggestions applies to what is happening.
The fonts on the websites I mentioned are not garbled and fonts on my machine are not corrupted.
The characters on the pages in question are correct, just spaced too far apart or appearing in the wrong places, e.g. scattered around the page or scrunched up in narrow columns.
In addition, portions of some web sites are enormously stretched horizontally, too, which leaves long horizontal gaps in between some words and characters.... and also makes it so that even my 1920x1200 monitor can't display, for example, the top header of Amazon.com without horizontal scrolling. Other portions of that page are a normal width, but I have to scroll way over to log in or find "view cart".
It seems to me more like the css for those sites is not being read or interpreted correctly.
Also, some sites appear normal, while others display these problems.
Something like this is happening in Safari too, though, I have discovered. Hmmm.
I should mention, too, that the sites look normal in an old version of Firefox I happen to have on an older Mac here, version 2.0.20. It's obsolete for some things, true, but it displays these problem sites perfectly.
And the problem does NOT happen in Opera at all (latest version)!
All the sites I gave as examples look completely normal in Opera!
Hmmm. I will have to start browsing with Opera, it appears if I can't find the answer.... :-( I usually only use it to check pages I have designed.