I'd suggest we go back to using the same fonts for body and headers.
It has been confusing/problematic having the h1/h2 using serif, and everything else using sans-serif. Related Vector tasks:

• T73240: Re-evaluate serif font stack for headers
• T65844: h3 should not be more prominent than h2 headings
• T72004: h4, h5, and h6 headers should not have the same styling

In T173228#3543659, @Quiddity wrote:

I'd suggest we go back to using the same fonts for body and headers.

This would solve so many problems.

It has been confusing/problematic having the h1/h2 using serif, and everything else using sans-serif.

Well, that's sort of solved here by just having all headers use serif, and some other interfacey things too, but then we wind up with the issue of when to use it where...

Also the content fonts are dumb.

Another idea:

<RileyBugz> Why not use times or something for the article title, and just use sans-serif for the rest

In relation to this, I find the fact that things with the "dt" tag are in a serif font; I think it would look better for it to just be a bolded sans-serif font.

There are also multiple font names for Linux Libertine, for some reason, so the CSS should match 'Linux Libertine', 'Linux Libertine O' and 'Linux Libertine G' in that order (if it's kept).

At the very least, I feel like Times should be included as an option, because of it's ligatures.

By the way, I propose changing the code to this:

@fonts: sans-serif;
@fonts-secondary: 'Times', 'Times New Roman', sans-serif;

and for screen-common.less:

h2,
h3,
h4,
h5,
h6,
dt {
font-family: @fonts;
}

dt {
font-weight: bold;
}