Improve the done button visibility

LeCountdown/Views/StartView.swift

@@ -77,7 +77,11 @@ struct StartView: View {
                     .font(.title2).fontWeight(.semibold)
                     .padding()
                     .frame(maxWidth: .infinity)
-                    .background(.white)
+                    .foregroundColor(.white)
+                    .background(Color.accentColor)
+                    .cornerRadius(12.0)
+                    .padding(.horizontal, 4.0)
+
             }
 
         }