Answers for "bootstrap small-6"

columns center bootstrap 3

<div class="row">
    <div class="col-md-2 col-md-offset-5"></div>
</div>

bootstrap breakpoints

// Small devices (landscape phones, 576px and up)
@media (min-width: 576px) { ... }

// Medium devices (tablets, 768px and up)
@media (min-width: 768px) { ... }

// Large devices (desktops, 992px and up)
@media (min-width: 992px) { ... }

// Extra large devices (large desktops, 1200px and up)
@media (min-width: 1200px) { ... }