CSS :not(:last-child):after selector

Answer 1

If it's a problem with the not selector, you can set all of them and override the last one

li:after
{
  content: ' |';
}
li:last-child:after
{
  content: '';
}

or if you can use before, no need for last-child

li+li:before
{
  content: '| ';
}