[Initial Post]
Overriding the
col-lg-12
class in your page might help. Write like below.
#divId .col-lg-12{
width: 1200px !important;
}
[Update]
So, me and OP tried together and solved it !!! This is called partnership. :)
The below is his idea which seems to be similar as mine.
@media (min-width: 1200px) {
.BackLight {
width: 1170px !important;
float: none !important;
}
}