Sidebar nested menu expand/collapse has no animation (feels abrupt) #2778
Description
Describe the problem
First of all, thank you for Redoc — I use it frequently and it is very useful.
One UX gap I keep noticing is the left sidebar nested menu behavior:
expand/collapse is currently abrupt (no transition), which feels less modern than the rest of the UI.
Current behavior
When toggling nested items in the left sidebar, the submenu appears/disappears immediately.
Expected behavior
Submenu expand/collapse should animate smoothly (height-based accordion transition), while preserving current behavior:
- active state handling
- scroll syncing / auto-follow behavior
- keyboard interaction and ARIA semantics
- mobile and desktop layout stability
- reduced motion support (
prefers-reduced-motion)
Why this matters
The sidebar is a primary navigation surface in Redoc. Smoother transitions improve perceived quality and readability, especially in large specs.
Additional context
I already prepared a small, focused implementation and can open a PR if this direction is acceptable.