Oh I understand the style, I just think it's backwards. The whole point of CSS is to move the styling out of the markup, and this obviously fails atrociously in that regard.
Each class is one CSS property, where it would be literally less verbose to just inline them. It's exactly the same thing as doing style="prop: value; prop: value;" since to change a given area of text from grey to black you'd have to edit every single element the same way.