diff --git a/internal/tui/model.go b/internal/tui/model.go
index b6f86ff..d49e20d 100644
--- a/internal/tui/model.go
+++ b/internal/tui/model.go
@@ -82,6 +82,10 @@ type Model struct {
 	flowList            list.Model
 	viewport            viewport.Model
 
+	// Packet Details View
+	detailsViewport    viewport.Model
+	focusPacketDetails bool
+
 	// File browser for pcap import
 	fileBrowser    FileBrowserModel
 	loadedPcapPath string
@@ -568,42 +572,60 @@ func (m *Model) updateSubView(msg tea.Msg) (tea.Model, tea.Cmd) {
 
 	case SubViewCallDetail:
 		var cmd tea.Cmd
-		// We handle scrolling manually via selection now
+
+		// Handle Focus Switching
 		if keyMsg, ok := msg.(tea.KeyMsg); ok {
 			switch keyMsg.String() {
 			case "esc", "q":
 				m.subView = SubViewNone
 				m.selectedPacketIndex = 0 // Reset selection
+				m.focusPacketDetails = false
 				return m, nil
-			case "up", "k":
-				if m.selectedPacketIndex > 0 {
-					m.selectedPacketIndex--
-					// Sync viewport
-					if m.selectedPacketIndex < m.viewport.YOffset {
-						m.viewport.SetYOffset(m.selectedPacketIndex)
-					}
-				}
-			case "down", "j":
-				flows := m.callFlowStore.GetRecentFlows(20)
-				if m.selectedFlow < len(flows) {
-					flow := flows[m.selectedFlow]
-					if m.selectedPacketIndex < len(flow.Packets)-1 {
-						m.selectedPacketIndex++
+			case "tab":
+				m.focusPacketDetails = !m.focusPacketDetails
+				return m, nil
+			}
+		}
+
+		// Route keys based on focus
+		if m.focusPacketDetails {
+			// Forward keys to Details Viewport for scrolling
+			m.detailsViewport, cmd = m.detailsViewport.Update(msg)
+			return m, cmd
+		} else {
+			// Handle Flow Navigation
+			if keyMsg, ok := msg.(tea.KeyMsg); ok {
+				switch keyMsg.String() {
+				case "up", "k":
+					if m.selectedPacketIndex > 0 {
+						m.selectedPacketIndex--
 						// Sync viewport
-						if m.selectedPacketIndex >= m.viewport.YOffset+m.viewport.Height {
-							m.viewport.SetYOffset(m.selectedPacketIndex - m.viewport.Height + 1)
+						if m.selectedPacketIndex < m.viewport.YOffset {
+							m.viewport.SetYOffset(m.selectedPacketIndex)
+						}
+						// Force update of details content happens in View currently, but for state consistency
+						// we should probably do it here or let View handle it.
+						// Since View is pure function of state, it's fine.
+						// But detailsViewport scroll position should reset if packet changes?
+						m.detailsViewport.GotoTop()
+					}
+				case "down", "j":
+					flows := m.callFlowStore.GetRecentFlows(20)
+					if m.selectedFlow < len(flows) {
+						flow := flows[m.selectedFlow]
+						if m.selectedPacketIndex < len(flow.Packets)-1 {
+							m.selectedPacketIndex++
+							// Sync viewport
+							if m.selectedPacketIndex >= m.viewport.YOffset+m.viewport.Height {
+								m.viewport.SetYOffset(m.selectedPacketIndex - m.viewport.Height + 1)
+							}
+							m.detailsViewport.GotoTop()
 						}
 					}
 				}
 			}
 		}
 
-		// We generally don't need viewport.Update for keys anymore as we handle scroll manually
-		// But we might need it for resizing or other generic msgs?
-		// Actually viewport.Update handles scroll keys by default.
-		// If we return cmd from it, it might conflict.
-		// Let's NOT call viewport.Update for keys if we consumed them.
-
 		return m, cmd
 	}
 
@@ -889,25 +911,22 @@ func (m Model) renderCallDetail() string {
 	}
 
 	// --- Left Pane BOTTOM (Selected Packet Details) ---
-	var leftBot strings.Builder
-	leftBot.WriteString(m.styles.Title.Render("📦 Packet Details"))
-	leftBot.WriteString("\n\n")
-
+	var detailsContent string
 	if m.selectedPacketIndex < len(flow.Packets) {
 		pkt := flow.Packets[m.selectedPacketIndex]
-		leftBot.WriteString(fmt.Sprintf("Time: %s\n", pkt.Timestamp.Format("15:04:05.000")))
-		leftBot.WriteString(fmt.Sprintf("IP: %s -> %s\n\n", pkt.SourceIP, pkt.DestIP))
-
-		// Render Payload/Raw
-		// Truncate if too long?
-		raw := pkt.Raw
-		// Simple header parsing or just raw dump?
-		// Raw dump is useful.
-		leftBot.WriteString(raw)
+		detailsContent = fmt.Sprintf("Time: %s\nIP: %s -> %s\n\n%s",
+			pkt.Timestamp.Format("15:04:05.000"),
+			pkt.SourceIP, pkt.DestIP,
+			pkt.Raw)
 	} else {
-		leftBot.WriteString("No packet selected")
+		detailsContent = "No packet selected"
 	}
 
+	// Update details viewport content
+	m.detailsViewport.SetContent(detailsContent)
+	m.detailsViewport.Width = leftW - 2 // Account for padding/borders roughly
+	m.detailsViewport.Height = leftBotH
+
 	// --- Right Pane (Transaction Flow) ---
 	var right strings.Builder
 	// right.WriteString("Transaction Flow:\n\n") // Removed header to save space or added to viewport content
@@ -988,14 +1007,25 @@ func (m Model) renderCallDetail() string {
 	// Set content to viewport
 	m.viewport.SetContent(right.String())
 
+	// Determine Border Colors based on Focus
+	detailsBorderColor := lipgloss.Color("#44475A")
+	flowBorderColor := lipgloss.Color("#44475A")
+
+	if m.focusPacketDetails {
+		detailsBorderColor = lipgloss.Color("#bd93f9") // Active Purple
+	} else {
+		flowBorderColor = lipgloss.Color("#bd93f9")
+	}
+
 	// Layout Construction
 	leftTopStyle := lipgloss.NewStyle().Width(leftW).Height(leftTopH).Padding(1, 2)
-	leftBotStyle := lipgloss.NewStyle().Width(leftW).Height(leftBotH).Padding(1, 2).Border(lipgloss.NormalBorder(), true, false, false, false).BorderForeground(lipgloss.Color("#44475A")) // Top border for bottom pane
-	rightStyle := lipgloss.NewStyle().Width(rightW).Padding(0, 1).Border(lipgloss.NormalBorder(), false, false, false, true).BorderForeground(lipgloss.Color("#44475A"))                   // Left border for right pane
+	leftBotStyle := lipgloss.NewStyle().Width(leftW).Height(leftBotH).Padding(0, 1).Border(lipgloss.NormalBorder(), true, false, false, false).BorderForeground(detailsBorderColor)
+	rightStyle := lipgloss.NewStyle().Width(rightW).Padding(0, 1).Border(lipgloss.NormalBorder(), false, false, false, true).BorderForeground(flowBorderColor)
 
 	// Render left pane parts
 	leftTopRendered := leftTopStyle.Render(leftTop.String())
-	leftBotRendered := leftBotStyle.Render(leftBot.String())
+	// Use detailsViewport view
+	leftBotRendered := leftBotStyle.Render(m.detailsViewport.View())
 
 	// Combine Left
 	leftCol := lipgloss.JoinVertical(lipgloss.Left, leftTopRendered, leftBotRendered)