This again should represent a review from what you've already covered in the Foundations Lesson on HTML/CSS, but if you're unable to answer the questions posed below in the "Learning Outcomes" section, you could probably benefit from the review of the basic stuff.
What are selectors?
In general, how specific should you be when targeting elements using selectors?
What's the difference between using %, em and rem to specify sizes?
How do you select an element inside another element?
How can you shorten up a long batch of CSS that's doing the same thing to many different elements by putting them all in one line?
How do you target the immediate child of an element?
How do you target a class inside a class?
How do you target a class inside an ID?
How would you target "all the links inside li elements that have the class bunny which are inside the unordered list with the id things-that-hop"?
What are the three ways to include CSS in your project?
How do you import an external stylesheet?
What is the browser's default stylesheet?
What is a "CSS Reset" file and why is it helpful?
Which stylesheet has preference if you import multiple ones and there are overlapping styles?
What is the order of priority of selectors (e.g. if you specify that the <body> has color black but <h1> tags have the color blue but class main-title has the color red, which will be used by <body style="color:yellow"><h1 class="main-title" style="color:green">Howdy!</h1><body>?)