Two columns that stack on a phone in HTML & CSS
HTML & CSS interview exercise on Responsive, 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.
Two equal columns with a 24px gap on screens 640px and wider; below that, one column with the second block under the first and 24px between them. Mobile first: write the single-column rule plainly and add the two-column layout in a min-width media query.
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.