The leaves are drooping

This is exactly how a new born seedling should look, you don't have any issues. The cotyledons (small round leaves) only job is to protect the growing tip as it pushes up through the soil. After this they serve no function to the plant and usually go yellow and die withing 7-10 days, which again is perfectly normal and not an issue. For the cotyledons to peel back and droop down is exactly what they are meant to do, that is to expose the first true leaves, the serrated ones, to as much light as possible and start the journey in life. Forget the humidity dome, it is not needed, but good air exchange is and also some air movement is also needed, to strengthen the stem, which are two things that don't occur when your seedling is inside a humidity dome. The notion that cannabis needs high humidity is an outdated concept from the 1960s when no one new much about how cannabis grows and thought it came from jungles or rain forests, which it certainly does not. The high humidity inside a "dome" can cause fungal diseases, stretching of the stem and overly high temps that can actually cook your seedling to death. It is a wonder that cannabis has survived for hundreds of thousands of years in nature without little elves placing little humidity domes over them when they were babies to keep them nice and toasty! Hope this helps, Organoman.