Very simple problem with a pretty complicated solution, mostly because IE is ignoring the box-shadow CSS3 property. Instead progid:DXImageTransform.Microsoft.Shadow is doing the trick for it and an equivalent can be found.
Styling a form is never an easy thing to do, but adding CSS3 on a HTML5 form is a task that shows a large variety of results when it comes to testing on different browsers. Check the test link.
When it comes to CSS3 not much can be done: but adding rounded corners, gradients and dropshadows is still more than nothing anf the overall aspect of the form is waaaaaaaaay better. But HTML5 is supported by few browsers (this HTML form only by Opera) and CSS3 also by few broswers – but different from the one supporting HTML5.