<!DOCTYPE html>
<title>::before { display: inline-block; }</title>
<style>
ul li {
  list-style-type: none;
  counter-increment: item;
}
ul li::before {
  content: counter(item);
  display: inline-block;
  width: 3em;
}
ul {
  margin-left: 3em;
  padding-left: 0;
}
</style>
<ul>
<li>Foo
<li>Bar
</ul>