make element center of column bootstrap code example

Example 1: columns center bootstrap 3

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

Example 2: alighn right boostrap 4

<div class="float-left">Float left on all viewport sizes</div><br>
<div class="float-right">Float right on all viewport sizes</div><br>
<div class="float-none">Don't float on all viewport sizes</div>