Comment 7 for bug 995330

I've found a workaround that works on my machine...

1. Uninstall LibreOffice (I did a purge as shown below)
$ sudo apt-get --purge remove mozilla-libreoffice libreoffice*

2. Install OpenOffice (relax, that's a transitional package so you'll end up with LibreOffice only)
$ sudo apt-get install openoffice.org

That's it! Now when you open Calc or other LibreOffice programs, their menus should have normal look and the no-border issue should be gone.

Optionally, if you want to have additional UI styles available in LibreOffice, you can install the style packages as shown below:

$ sudo apt-get install openoffice.org-style-*

This will add a bunch of styles that you can choose from for your office programs from Tools | Options... menu and then navigating to the LibreOffice | View section.

Finally, if you prefer enabling opening LibreOffice documents directly in Firefox, you can install the mozilla-openoffice.org package:

$ sudo apt-get install mozilla-openoffice.org

Hope this helps.