AMP pages can’t include external stylesheets, with the exception of custom fonts. You can embed custom fonts into your page in two ways:

  1. Through a <link> tag (white-listed font providers only)
  2. Via @font-face (no restrictions, all fonts allowed)

Use a <link> tag (usually in the head of your page), like so:

<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Tangerine">

The following origins are whitelisted and allowed for font serving via link tags:

  • Typography.com: https://cloud.typography.com
  • Fonts.com: https://fast.fonts.net
  • Google Fonts: https://fonts.googleapis.com
  • Font Awesome: https://maxcdn.bootstrapcdn.com

2. Using @font-face

Alternatively, you can use @font-face within your AMP stylesheet:

<style amp-custom>
  @font-face {
    font-family: "Bitstream Vera Serif Bold";
    src: url("https://somedomain.org/VeraSeBd.ttf");
  }

  body {
    font-family: "Bitstream Vera Serif Bold", serif;
  }
</style>