Bootstrap push div content to new line
Do a row div.
Like this:
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.3/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-Zug+QiDoJOrZ5t4lssLdxGhVrurbmBWopoEl+M6BdEfwnCJZtKxi1KgxUyJq13dy" crossorigin="anonymous">
<div class="grid">
<div class="row">
<div class="col-lg-3 col-md-3 col-sm-3 col-xs-12 bg-success">Under me should be a DIV</div>
<div class="col-lg-6 col-md-6 col-sm-5 col-xs-12 bg-danger">Under me should be a DIV</div>
</div>
<div class="row">
<div class="col-lg-3 col-md-3 col-sm-4 col-xs-12 bg-warning">I am the last DIV</div>
</div>
</div>If your your list is dynamically generated with unknown number and your target is to always have last div in a new line set last div class to "col-xl-12" and remove other classes so it will always take a full row.
This is a copy of your code corrected so that last div always occupy a full row (I although removed unnecessary classes).
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet">
<div class="grid">
<div class="row">
<div class="col-sm-3">Under me should be a DIV</div>
<div class="col-md-6 col-sm-5">Under me should be a DIV</div>
<div class="col-xl-12">I am the last DIV and I always take a full row for my self!!</div>
</div>
</div>