Layers in SL360 - Are they transparent or solid?

Hello everyone,

I just wanted to ask a question about layers.

Are they transparent or solid?

Example: I have a project with a base layer that has four options that allows me to access four different layers. When I select option 1 in my menu it takes me to layer 1. Should I still be able to access the menu now that sits on the base layer or, because I am on layer 1, will my menu now not be accessible?

Reason for all this is that when I am working on a project everything all seems to suggest that layers are transparent unless I put large rectangles of solid colour on my layer in which case those parts of the layer are now solid and whatever sits underneath those solid rectangles can't be accessed.

I then publish out my project and put it on our LMS and the layers appear solid now in that anything that sits beneath the selected layer in non functional.

Hope that makes sense.
Any thoughts would be welcome.
Regards
Frazer