ChatGPT Website Works on Desktop But Not Mobile
Why generated layouts often fail on mobile and what to inspect first.
A ChatGPT-built website can look fine on a desktop screen and still fail badly on mobile. This usually happens because the generated layout was written for the example viewport, not the full range of real devices and content lengths.
Fixed widths cause overflow
One of the most common problems is fixed-width design. A section, card, image, form or navigation item may have a width that fits a laptop but exceeds a phone screen. The result is horizontal scrolling, clipped buttons or content that disappears off the edge.

Generated CSS may also combine fixed widths with padding, gaps or absolute positioning. Each rule might look reasonable alone, but together they can make a mobile layout unusable.
Responsive rules need real testing
A media query is not a guarantee of responsive design. The site still needs to be tested at multiple widths, with long headings, real form labels, menus, buttons and embedded content. A layout that works at 390px may still break at 320px or on a tablet.
Forms and navigation often fail first
Mobile problems show up quickly in forms and navigation. Fields may be too narrow, buttons may wrap badly, menus may overlap content, and sticky elements may cover the submit button. These issues directly affect enquiries and conversions.
Images and embeds can break the page
Generated code may not include responsive constraints for images, videos, maps or third-party widgets. A single wide embed can cause the whole page to overflow. Every fixed-format element needs a maximum width and sensible mobile behaviour.
Repair the layout in context
Do not judge the code only by the prompt output. Test the live page inside the real theme and browser. Use developer tools to find the element causing overflow, then simplify the structure and responsive rules.
If your ChatGPT-built website works on desktop but not mobile, ChatGPT Website Repair can inspect the layout and repair the failing breakpoints. When menus, forms and service pages all suffer on phones, repair the full mobile journey rather than one section at a time.