Fix font in how-to end screen

[kyleplo]

Expected Behavior

The buttons use a normal font.

Actual Behavior

The buttons use the default font because Helvetica Neue is not supported. Most likely related to lines 163 and 199 of /src/components/cards/card.css

Steps to Reproduce

Open any how-to and go to last screen

Operating System and Browser

Chrome 66 Windows 10

[paulkaplan]

Note also happens in Edge, #2191