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.

Tabs

How do we accomplish this?

  1. Go to Codeplex: https://sharepointtabs.codeplex.com/releases/view/117882
  2. Download page template
  3. Add to your page gallery (Make sure to select Page Layout content type)
  4. Make a page.
  5. Put web parts in correct zone.
  6. Works like a charm

Read full blog post on Paul’s site.