Mobile phone / Navi reflects extreme

Hello all, I use my mobile phone as a navigator on the motorcycle. I put it in the card pocket on the tank backpack. Now I have the following problem: The mobile phone display is hardly visible in strong sunshine, the foil from the card pocket makes this even worse. I set the phone to full brightness. This causes that I actually always have to go right to read the track and that’s quite annoying. How do you do that? Is there a trick or a slide or something with which the solar radiation is dampened so that you can recognize the display ? Or you just have to get a (motorcycle) Navi that has a display which is still easy to recognize even with solar radiation ? Would like to stay with my mobile phone as a Navi, but if I can see almost nothing during the ride that does not bring much… Greeting, Mac