go Today’s post is quick how to when working with SharePoint Online Master page.
here When working with SharePoint Online oslo master page, you will find that usual way of hiding gear icon would not work i.e. you will not find the div for s4-ribbonrow. Seattle.master still has that.
cheapest place to buy finast Reason for that is because Oslo and Seattle are different master page. You can read about the difference in the following blog post.
Coming back to hiding the gear icon you can target the button ID to hide it.
Either in your CSS or Script Editor web part add the following Style.
Where O365_MainLink_Settings is the ID of Settings button.
I hope this helps someone.