Added the following code to my index.php to shore up the menu:
<form name=”archiveform” action=””>
<select name=”archive_chrono” onchange=”window.location = (document.forms.archiveform.archive_chrono[document.forms.archiveform.archive_chrono.selectedIndex].value);”>
<option value=”>By Month</option>
<?php get_archives(”,”,’option’, 1); ?>
</select>
</form>
Not the CSS solution I wanted, but the result is the same.