copy styled text from div into textarea

You can't put HTML content within a text area because it's displayed as-is (e.g. HTML source).
What you can do is to create a div of a fixed size with the overflow set to scrolling, for example:
HTML Code:

XML

<style type="text/css">
div.terms
{
  width: 20em;
  height: 15em;
  overflow: auto;
}
</style>

<div class="terms">
  Terms and conditions<br />
  <br />
  <br />
  Blah blah.. <img src="/whatever.png" alt="blah" />
</div>