CDN doesn't serve certain characters included in some fonts

**Describe the issue**
The Google Fonts CDN doesn't serve all characters available in some fonts. This is especially noticeable with fonts that support the box drawing unicode range, U+2500-257F (for example, [Fira Code](https://fonts.google.com/specimen/Fira+Code)), while trying to use the Box Drawing Light Arc characters, U+256D-2570.

**To Reproduce**
Produce the CSS and HTML such that they render box drawing characters (best done with `

` and a monospace font) and use a font from the Google fonts CDN that supports those characters (such as Fira Code). Note the results.


Clone the above HTML/CSS and adjust it to instead use one of the font files (by either hosting the file yourself or encoding as a data URI and using that) available in the downloadable zip files for the font. Note the results.

Note the differences between the two examples.

**Expected behavior**

The CDN should be serving CSS and font files that contain all characters available in original font files.