This could be a change in Firefox, but if the site specifies the sans-serif font family, then Firefox likely will use the font you specify as your default sans-serif font. If you want to always see a serif font, change the default sans-serif font to a serif face.

Also, when settings fonts, you may need to change two character sets: Latin and Other Writing Systems. (I think those are the two most commonly used.) There is a selector at the top of the Fonts dialog to choose the character set.

Does that work?

Thanks jscher2000, but unfortunately this doesn't work. I have selected Times as both my preferred serif and sans-serif face, in both Latin and Other Writing Systems character sets, and am still seeing everything in sans serif.

Note that in some cases you may see a little box with the hex code if a website uses an icon font that is downloaded from the server to display small images.

In Firefox 41 and later this works better than before with website fonts disabled.

• http://www.ghacks.net/2015/07/21/firefox-41-mozilla-modifies-how-icon-fonts-are-handled-by-the-browser/

Still doesn't make the change I was anticipating, but thank you for the post.

You can use the Stylish extension or code in userContent.css to override the font on pages that you visit a lot (e.g. daily). For instance I make a lot of changes to the appearance of forum pages because I spend a lot of time here and the layout isn't always that much "eyes friendly" for me. I prefer one font size and a text color with enough contrast and use a monospace font (.answers .main-content{font-family:dejavu sans mono,monospace}) for letter spacing and avoid confusion between an 'l' (L) and 'I' (i).

Example: Add code to the userContent.css file.

• http://kb.mozillazine.org/userContent.css

@-moz-document domain(support.mozilla.org){
 .answers .main-content,
 .questions > section .content .long-text,
 .questions > section .content .short-text,
 input[type="text"],textarea {
  color:#000;
  font-family:monospace!important;
 }
}

The customization files userChrome.css (user interface) and userContent.css (websites) are located in the chrome folder in the Firefox profile folder.

• http://kb.mozillazine.org/Editing_configuration

See also:

• https://developer.mozilla.org/en/CSS/@document

You can right-click and select "Inspect Element" to open the Inspector (Firefox menu button or Tools > Web Developer) with this element selected. You can check the font used for selected text in the Font tab in the right pane of the Inspector.

• https://developer.mozilla.org/Tools/Page_Inspector

I'm not very familiar with Mac fonts. When you say you selected "Times" do you mean the full name is "Times"? Do you have any better luck with "Times New Roman"?

Setting my default fonts to Times, rather than Times New Roman, is all it took -- but thanks to everyone for your exceptional tech skills and advice!

It is a real pleasure to be able to read things again.