How to display 12 grid for development purpose in bootstrap? I am using bootstrap theme and create child theme. i want to display 12 grid for development purpose. 

Can any body tell me how to enable this?

Thanks
You could try adding a image of the grid as a css background image to the container class. This might fail if you are overriding it for any reason. 

A more difficult way of achieving this would to try having a grid fixed position over your site that you can maybe toggle with JavaScript.