On Mozilla Firefox (on GNU/Linux) with default font and UTF-8 encoding, I am seeing some websites, such as GitHub, display weird characters across the page.

Weird behavior

Under a different browser, such as WebKit based, the site looks normal.

What is causing these icons or glyphs to appear when I view such sites?


If a website viewed in Firefox looks like it's all jacked up but in other browsers it's okay then you may have switched off allowing the site to download and/or display a custom font.

This is usually the case if you are seeing gibberish like a small box with numbers and letters on top of each other on parts of the website where you would expect to see custom icons.

To fix this, go to

Tools → Options → Content → Fonts & Colors → Advanced

Make sure the following has a check mark in the box:

☑ Allow characters to choose their own fonts, instead of my selections above

OK, OK, and you will now see the font icons the site has set up.

  • 1
    Note: This also applies to Firefox' internal PDF viewer (pdf.js). If "Allow characters to choose their own fonts[...]" is disabled, most PDF files will look very weird, because all text will use the default font. – sleske Feb 6 '13 at 23:35

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