Knowledge Base · Infrastructure & deployment
A page that would not scroll: overflow and an unpositioned overlay
The symptom
The wheel and touch gestures did nothing. The page appeared complete but immovable, and a dialog's backdrop sat over the content permanently.
What was actually wrong
Three unrelated defects stacked: the root element had vertical overflow suppressed, the body still hid overflow instead of allowing it, and the overlay markup had no positioning rule at all — so instead of a modal layer that appears on demand, an unstyled block sat in the flow. Separately, the same page's API calls were failing because the web server had no route for them, so they fell through to an unrelated handler.
The fix
Restore scrolling at the root and stop hiding overflow on the body, give the overlay fixed positioning with a backdrop and an opacity transition, and add explicit proxy locations for every API path the page calls rather than relying on a catch-all.
What we took away
A frozen page is rarely a JavaScript problem: check overflow on the root and body first, then positioning on overlays. And every new API path the front end calls should be an explicit route in the web server, not something you hope the catch-all handles.