This works without JavaScript or CSS in most browsers:
<form>
<p><input type="text" name="field1" /></p>
<p><a href="previous.html">
<button type="button">Previous Page</button></a>
<button type="submit">Next Page</button></p>
</form>
Firefox, Opera, Safari, and Google Chrome all work.
As always, Internet Explorer is the problem.
This version works when JavaScript is turned on:
<form>
<p><input type="text" name="field1" /></p>
<p><a href="previous.html">
<button type="button" onclick="window.location='previous.html'">Previous Page</button></a>
<button type="submit">Next Page</button></p>
</form>
So the flaw in this solution is:
Previous Page does not work if you use Internet Explorer with JavaScript off.
Mind you, the back button still works!