In the exercise last line, it says "Make sure to capitalize the first letter of Arial, Verdana, and Impact as shown!"
I don't think this is correct. You don't have to capitalize the font-family name. The W3C standard requires that browsers match font names case insensitively using a specific algorithm. In fact, web browsers have treated font-family names case insensitively long before that standards document made it official. See https://www.w3.org/TR/css-fonts-3/#font-family-casing
I believe it just needs more explanation that instructs on appropriate styling to new learners instead of making it sound like proper casing is necessary and parsing is case sensitive.