The official TodoMVC CSS uses ids (#foo) which in a ComponentJS application prevents components from being rendered multiple times and hence is a major "don't do it this way". Instead one uses classes (.foo) only, optionally even in BEM-style. This way a component can be instanciated arbitrary times into the component tree and even rendered into the DOM multiple times. For the particular TodoMVC scenario (where the TODO list is rendered just once on the screen) I could have used the official CSS 1:1, but it would show people the wrong "best practice" for a ComponentJS app. Second, the TodoMVC CSS is all just once large file. In ComponentJS each component is fully self-contained, from markup, over code to CSS. In a ComponentJS app one places the CSS of a component side-by-side to the markup and code of the component. For these two reasons I decided to follow the TodoMVC advise of "Try to follow this structure as close a possible while still keeping to the framework’s best practices." as the single id-based CSS is in conflict with this way of structuring an app with the help of ComponentJS.