eggdesign
Hi,
To change the col-lg-6 class, you need to change in layout file while the class you're mentioning for masthead is declared in blocks of template
You open file: root/templates/ja_mono/tpls/default.php
and see col-lg-6 is declared there.
If you want to have different classes used in different page, you can clone this default layout, then edit as you wish.
Then go to Backend > Extensions > Templates > clone JA Mono template style to have a new style > Layout tab > load the new layout you created.
And assign to the page you wish.
For more info about layout, pls check out this doc: http://www.t3-framework.org/documentation/bs3-layout-system#add-layout