fix: Update detailsViewport dimensions in Update loop to ensure scrollability

internal/tui/model.go

@@ -397,6 +397,39 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 
 		m.viewport.Width = m.width / 2 // Right pane width
 		m.viewport.Height = contentHeight
+
+		// Correctly calculate Split Layout Dimensions for Viewports
+		// Ideally we should share this logic or calculate it once
+		totalWidth := m.width
+		innerW := totalWidth - 2
+		leftW := innerW / 2
+		rightW := innerW - leftW
+
+		leftTotalH := m.height - 3
+		leftTopH := leftTotalH / 3
+		if leftTopH < 10 {
+			leftTopH = 10
+		}
+		leftBotH := leftTotalH - leftTopH
+		if leftBotH < 0 {
+			leftBotH = 0
+		}
+
+		// Update Flow Viewport (Right)
+		rvpHeight := (leftTotalH - 2) - 2 // -2 Borders, -2 Title
+		if rvpHeight < 0 {
+			rvpHeight = 0
+		}
+		m.viewport.Height = rvpHeight
+		m.viewport.Width = rightW - 4
+
+		// Update Details Viewport (Left Bottom)
+		vpHeight := (leftBotH - 2) - 2 // -2 Borders, -2 Title
+		if vpHeight < 0 {
+			vpHeight = 0
+		}
+		m.detailsViewport.Height = vpHeight
+		m.detailsViewport.Width = leftW - 4
 	}
 
 	return m, tea.Batch(cmds...)