Change grid columns to 16

Hi !
I'm using t3 bs3 blank template and trying to change the @grid-columns to 16.
I believed changing

@grid-columns:  12; 

in

@grid-columns:  16;

should do the trick perhaps when I go back on the backend and try to change the Responsive Layout of my style the maximum columns is 12...

On the other side the frontend upgrade the .container elements to 16 columns

Any idears ?

Regards

Ben