A header that sticks in HTML & CSS
HTML & CSS interview exercise on Positioning & stacking, difficulty 1 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.
Keep the header at the top of the viewport while the page scrolls, without taking it out of the flow (the content must start below it, not under it). It should also sit above the content that scrolls past.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.