Centring with auto
Level 7 of 13Your goal
Keep the box 200 × 80 and centre it horizontally at both stage widths: x = 110 on the 420px stage and x = 250 on the 700px stage.
Must use
marginChecked at 2 stage widths (420px, 700px) — every stage below has to match.
stage 420px
stage 700px
marginborderpaddingcontenttarget content boxtarget outer edge (green = matched, red = not yet)
Feedback updates as you type, and your CSS is saved in this browser. Exact target numbers are in the Target panel.