Could someone please explain why this does not display properly on any other browser except IE:

<span id="NextOfKinUniqueIDBuddy" class="ReadOnly" style="width:400px;height:50px; border:2px inset threedhighlight;padding:1px">
 <span id="1309819582156">
  <div>Dr Dre Aftermath</div>
  <div>1 Test Street, SYDNEY, NSW 2000 AU</div>
  <div>Phone: +61 02 98222222 Fax: +61 02 91111111 Mobile: 0415875421</div>

I'm aware that threedhighlight may not be compatible with other browsers, but nothing else seems to work (e.g. changing the background-color to black)

Any help is greatly appreciated.

Many thanks

Use DIV tag instead of the first SPAN tag and remove the height CSS.

SPAN is inline element and DIV is block. Inline element cannot contain block-level elements whether block-level element can contain both block and inline elements. Try to alter way to use.