This is an essential for the laptop as side arm. If you keep your laptop at the ready to prepare notes or type on impulse, you need to adapt your screen for sunlight. Waiting in the car provides ideal isolation for tackling backlogged projects if you can see the cursor. Early photographers faced a similar problem excluding light and solved it then. Hoods.
 
Here’s another easy remedy for laptops which run hot. This swivel base provides the extra clearance for air cooling, the usual benefits of being able to turn your laptop on an axis without scratching or shaking anything, and it takes almost no additional space in your bag.