New feature: add options to change "grids" back color, color and padding

We know that we can change this properites for each grid change the grid in the custom.css, or in the custom code tab or even in the yjsg_custom_params.php.

But we think the grid back color, color and padding are the most common things to change when you are changing the appearance of the template.

We have made this in our installation of your framework using template-settings.xml and yjsg_custom_params.php to dinamicly apply the new css.

But it would be nice to have it in the framework itself.
In attach theres a image of what we mean.