Good Morfnoevight All you happy Thursday Stoners!
60% RH is ok for seedlings, skip the domes.
Just look at the chart. if you keep the RH in the same column and you move the temperature up or down you can see the effect on VPD.
View attachment 1496638
For example at 60% RH and 80.6°F the VPD = 1.22 at 77°F the VPD = 1.08 so you can see as the temperature goes down with the RH constant the VPD also goes down.
Here in this desert valley it is nearly impossible for me to maintain VPD it just gets too dry here. My goal is to keep the RH between 40% and 60%. Most of the time I can do this.