I created an alternate CSS file with the goal of hiding the New Subsite button from a user in Onedrive for business. The CSS file contains one line:
#createnewsite{ display: none; }
and is saved in the style library for the root site of our personal sites (https://domain-my.sharepoint.com). I also enabled Server Publishing for this site collection.
I then went to the Master Page dialog for the site and set the alternate CSS URL to point to this file and selected the checkbox to propagate this css to all pages in this site. I assumed that this meant the CSS would be deployed to any new OD4B sites as well as existing ones.
However I don't see that changes taking place for existing OD4B users. I did spin up a new user and it appears to have taken effect for this user. Is there anything I can do to make this work for existing Onedrives? Thanks!