css/css-ui/outline-offset-inset-001-ref.html

<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-ui-4/#outline-offset">
<style>
  div {
    display: inline-block;
    width: 80px;
    height: 80px;
    background: lightblue;
    outline-style: solid;
    margin: 20px;
  }
  .w3  { outline-width: 3px;  outline-offset: -3px; }
  .w8  { outline-width: 8px;  outline-offset: -8px; }
  .w12 { outline-width: 12px; outline-offset: -12px; }
</style>
<div class="w3"></div>
<div class="w8"></div>
<div class="w12"></div>