Type about:preferences#content<enter> in the address bar. Across from fonts and colors, press the Advanced button. On the bottom, turn on Allow Web Sites To Choose Their Own.

Fonts Information - Detected via Flash http://browserspy.dk/fonts-flash.php?detail=1

The checkmark was already checked.

You can check what fonts Firefox is using in both cases.

You can right-click and select "Inspect Element" to open the builtin Inspector with this element selected.

• https://developer.mozilla.org/en-US/Tools/Page_Inspector/How_to/Examine_and_edit_HTML

You can check in the Rules tab in the right panel in the Inspector what font-family is used for selected text. You can check in the Font tab in the right panel in the Inspector what font is actually used because Firefox might be using a different font than specified by the website.

• https://developer.mozilla.org/en-US/Tools/Page_Inspector/How_to/Edit_fonts

The fonts it is using are:

• Roboto
• Microsoft YaHei
• Yu Gothic

It may be possible that some characters are displayed with one font and others with another. How would I check for that?

You can select an individual character and check this character in the Inspector.

Apparently some of the text is in Microsoft YaHei and some of it is in Yu Gothic. How can I make it so that it is consistent?

So I just reinstalled Firefox and now it is one consistent font (Microsoft YaHei).

SchoolBusesC2 said

So I just reinstalled Firefox and now it is one consistent font (Microsoft YaHei).