Best Value: candidate-priced fills, key copy, detail total

FuelBoard/StationsView.swift

@@ -249,7 +249,7 @@ struct StationsView: View {
                             VStack(spacing: 10) {
                                 keyCard(
                                     icon: "checkmark.circle.fill", color: .green,
-                                    title: "Best value", blurb: "Within 1.5p of the cheapest",
+                                    title: "Good price", blurb: "Within 1.5p of the cheapest",
                                     threshold: "≤1.5p")
                                 keyCard(
                                     icon: "equal.circle.fill", color: .orange,
@@ -298,6 +298,17 @@ struct StationsView: View {
                             .listRowBackground(Color.clear)
                             .listRowInsets(EdgeInsets(top: 4, leading: 16, bottom: 4, trailing: 16))
                         }
+
+                        Section("How Best Value works") {
+                            VStack(alignment: .leading, spacing: 10) {
+                                Text("Best Value compares each station with the closest one. It works out what you could save at the pump, then takes off the fuel used for the extra return journey.")
+                                Text("Your fill-up amount and MPG are used to show whether you could save overall.")
+                                Text("Results are marked “Approx.” until road distances are available.")
+                                    .foregroundStyle(.secondary)
+                            }
+                            .font(.subheadline)
+                            .padding(.vertical, 4)
+                        }
                     }
                     .navigationTitle("Key")
                     .navigationBarTitleDisplayMode(.inline)