In this great post by Paul Bauer you will find a simple way to add tabs to your O365 site- with no code. Works like dream.
How do we accomplish this?
- Go to Codeplex: https://sharepointtabs.codeplex.com/releases/view/117882
- Download page template
- Add to your page gallery (Make sure to select Page Layout content type)
- Make a page.
- Put web parts in correct zone.
- Works like a charm
Read full blog post on Paul’s site.