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, or cold in Interview mode with the example hidden; 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. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.