the best way i've found to keep lids just slightly up on any cooking device to allow reducing or thickening is to put a chopstick or a thin skewer under 1 end of the lid across the cooking vessel.
it keeps the lid fairly balanced to retain heat while giving enough space for the moisture to escape.
The way that you wander is the way that you choose. The day that you tarry is the day that you lose.
Sunshine or thunder, a man will always wonder where the fair wind blows.