navbar logo boostrap code example
Example: bootstrap navbar logo center
Try this:
.navbar {
position: relative;
}
.brand {
position: absolute;
left: 50%;
margin-left: -50px !important; /* 50% of your logo width */
display: block;
}
Centering your logo by 50% and minus half of your logo width so that it won't have problem when zooming in and out.