Answers for "bootstrap grid classes accessibility"

columns center bootstrap 3

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

bootstrap Accessibility

Since breadcrumbs provide a navigation, it’s a good idea to add a
meaningful label such as aria-label="breadcrumb" to describe the type 
of navigation provided in the <nav> element, as well as applying an 
aria-current="page" to the last item of the set to indicate that it 
represents the current page.