diff --git a/progress.txt b/progress.txt
index f16e559..8c71ece 100644
--- a/progress.txt
+++ b/progress.txt
@@ -994,3 +994,59 @@ All 4 phases (11 tasks) of the Pathway Data Architecture project are complete:
 
 ### Blocked items:
 - None
+
+## Iteration 16 — 2026-02-05
+### Task: 5.5 Top Bar Refinement
+### Why this task:
+- Previous iteration (15) completed Task 5.4 (Full-Width Chart Layout)
+- Task 5.5 was explicitly recommended as the next step
+- This is a polish task — the main structural work is done
+- Specific measurable goals: 48px height, 28px logo, smaller pills
+### Status: COMPLETE
+### What was done:
+1. **Added new imports** in pathways_app.py:
+   - top_bar_style, top_bar_tab_style, logo_style from styles.py
+
+2. **Updated chart_tab() function**:
+   - Now uses `top_bar_tab_style(active=is_active)` for consistent styling
+   - 28px height pills instead of larger pills
+   - Style properties extracted from helper instead of hardcoded
+
+3. **Updated top_bar() function**:
+   - Uses `logo_style()` for 28px logo (was 36px)
+   - Uses `top_bar_style()` for 48px height container
+   - Simplified data freshness to single line: "X records · Refreshed: 2m ago"
+   - Removed max_width constraint (full-width design)
+   - Tighter spacing (spacing="2" and "1")
+   - Lighter shadow (Shadows.SM instead of MD)
+   - Subtler tab background (0.08 opacity instead of 0.1)
+
+### Validation results:
+- Tier 1 (Code): [PASS] python -m py_compile passed
+- Tier 1 (Code): [PASS] Import check passed
+- Tier 1 (Code): [PASS] reflex compile succeeded (1.7s)
+- Tier 2 (Visual): Pending — requires reflex run to verify 48px height
+- Tier 3 (Functional): N/A (styling only)
+
+### Files changed:
+- `pathways_app/pathways_app.py` — Updated chart_tab(), top_bar() to use style helpers
+- `IMPLEMENTATION_PLAN.md` — Marked Task 5.5 subtasks complete
+
+### Committed: 754e98d "feat: refine top bar with style helpers (Task 5.5)"
+
+### Patterns discovered:
+- Style helper functions return dicts, use **style_helper() to spread
+- Can use style.get("property", default) to extract values for nested components
+- Removing max_width constraint allows full-width while keeping internal padding
+
+### Next iteration should:
+- Start Task 5.6: Visual Polish
+  - Add subtle hover states to interactive elements
+  - Ensure consistent focus rings for accessibility
+  - Test responsive behavior at common breakpoints (1366, 1920, 2560px)
+  - Remove any unused styles from styles.py
+- OR run visual verification with `reflex run` to confirm Tasks 5.2-5.5 visually
+- After Task 5.6, verify all completion criteria are met
+
+### Blocked items (Iteration 16):
+- None