---
id: T01
parent: S02
milestone: M011
provides: []
requires: []
affects: []
key_files: ["frontend/src/pages/TopicsBrowse.tsx", "frontend/src/App.css"]
key_decisions: ["Used CSS grid-template-rows 0fr/1fr technique for smooth height animation without JS measurement"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "TypeScript type check (npx tsc --noEmit) and production build (npm run build) both pass cleanly with exit code 0."
completed_at: 2026-03-31T08:30:49.223Z
blocker_discovered: false
---

# T01: Topics page loads with all categories collapsed; expand/collapse uses smooth CSS grid-template-rows animation instead of conditional render

> Topics page loads with all categories collapsed; expand/collapse uses smooth CSS grid-template-rows animation instead of conditional render

## What Happened
---
id: T01
parent: S02
milestone: M011
key_files:
  - frontend/src/pages/TopicsBrowse.tsx
  - frontend/src/App.css
key_decisions:
  - Used CSS grid-template-rows 0fr/1fr technique for smooth height animation without JS measurement
duration: ""
verification_result: passed
completed_at: 2026-03-31T08:30:49.224Z
blocker_discovered: false
---

# T01: Topics page loads with all categories collapsed; expand/collapse uses smooth CSS grid-template-rows animation instead of conditional render

**Topics page loads with all categories collapsed; expand/collapse uses smooth CSS grid-template-rows animation instead of conditional render**

## What Happened

Changed the useEffect in TopicsBrowse.tsx to initialize the expanded set as empty instead of pre-filling all category names. Replaced the conditional {isExpanded && (...)} render with an always-rendered wrapper div using the grid-template-rows: 0fr/1fr animation technique. Added CSS rules for the wrapper, expanded state, and updated the inner div with overflow: hidden and min-height: 0 for smooth clipping.

## Verification

TypeScript type check (npx tsc --noEmit) and production build (npm run build) both pass cleanly with exit code 0.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `cd frontend && npx tsc --noEmit && npm run build` | 0 | ✅ pass | 3700ms |


## Deviations

None.

## Known Issues

None.

## Files Created/Modified

- `frontend/src/pages/TopicsBrowse.tsx`
- `frontend/src/App.css`


## Deviations
None.

## Known Issues
None.
