<div class="m-n1 bg-primary d-inline-block">Negatively Spaced Div</div>
<!-- ... 1 to 5 -->
<div class="m-n5 bg-primary d-inline-block">Negatively Spaced Div</div>
<!-- directional viariations -->
<div class="mt-n4 bg-primary d-inline-block">Negatively Spaced Div</div>
<div class="mb-n5 bg-primary d-inline-block">Negatively Spaced Div</div>
<!-- ... t, b, r, l, x, y.. the whole gang-->
<!-- respsonsive viariations -->
<div class="m-sm-n3 d-inline-block bg-primary">Negatively Spaced Div</div>
<div class="m-md-n3 d-inline-block bg-primary">Negatively Spaced Div</div>
<div class="m-lg-n3 d-inline-block bg-primary">Negatively Spaced Div</div>
<div class="m-xl-n3 d-inline-block bg-primary">Negatively Spaced Div</div>
You don't need to remember all CSS classes. Just use the Bootstrap Editor instead.