<!DOCTYPE HTML>
<style>
p { width:200px; height:120px; background-color: lightgreen; }
.control { padding: -100px; }
.simple-px { padding: calc(100px - 200px); }
.simple-percent { padding: calc(50% - 60%); }
.mixed { padding: calc(1% - 100px); }
</style>
<div style="background-color: yellow;">
<p class="control">This element should have zero padding.</p>
<p class="simple-px">This element should have zero padding.</p>
<p class="simple-percent">This element should have zero padding.</p>
<p class="mixed">This element should have zero padding.</p>
</div>