Margin zero
Margin right zero
Margin bottom zero
Margin horizontal zero
Margin vertical zero
<div class="m0">Margin zero</div>
<div class="mr0">Margin right zero</div>
<div class="mb0">Margin bottom zero</div>
<div class="mh0">Margin horizontal zero</div>
<div class="mv0">Margin vertical zero</div>spacing.css, line 36