<!DOCTYPE HTML>
<meta charset="utf-8">
<title>Reference: Rel.pos. centered grid item with style change.</title>
<link rel="author" title="James0x57" href="mailto:James0x57@gmail.com">
<link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
<style>
.grid {
  margin: 40px;
  display: grid;
  grid: auto / repeat(3,100px);
  grid-gap: 20px;
}
span, even {
  position: relative;
  min-height: 20px;
  background: grey;
  left: 0px;
  width: 30px;
  justify-self: center;
}
.offset even {
  left: 20%;
}

</style>

<div class="grid offset">
  <span></span><span></span><span></span>
  <even></even><even></even><even></even>
  <span></span><span></span><span></span>
</div>