Feature Request: underline text

Spec
9

As a web designer, you can easily make text underlined with some simple CSS like this:

<style type="text/css">
  em {
    text-decoration: underline;
  }
</style>

*emphasis* can then be written in Markdown normally by the content writer, but styled differently for the particular website that it is used on.

I’m opposed to presentational elements in either HTML or Markdown because they violate the separation of concerns principle. It is the web designer’s job to decide how content is presented, not the content writer’s.