I'm working on share point online, as I'm trying to get rid of the access to site contents with read access, because the problem is that it has some custom forms in the site where users can add item to the list and what I wanted is user with read access should be able to add the items using the forms but shouldn't be able to access site contents which will give access to the list items submitted by other users. and also we are using few security groups for different subsites with permission level "contribute" and these users should be able to see the site contents.
it worked in the on-primise version with the custom permission level, but not working in the office 365.
how to achieve this, please ask if more information needed.
Thanks in advance