This show how to wrap a custom namespace around boostrap css.

namespaced-bootstrap.css

/*
    when build, this will prefix all rules with "namespaced-bootstrap"
*/
.namespaced-bootstrap {
    @import (less) url('https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css');
}

namespaced-bootstrap.html

<div class="namespaced-bootstrap"> <!-- yeah! -->

    <div class="panel panel-default">
      <div class="panel-body">
        Basic panel example
      </div>
    </div>

</div>