diff --git a/src/calibre/ebooks/mobi/mobiml.py b/src/calibre/ebooks/mobi/mobiml.py
index 1e626cf916..3c36a6166d 100644
--- a/src/calibre/ebooks/mobi/mobiml.py
+++ b/src/calibre/ebooks/mobi/mobiml.py
@@ -463,9 +463,9 @@ class MobiMLizer(object):
                 text = COLLAPSE.sub(' ', elem.text)
         valign = style['vertical-align']
         not_baseline = valign in ('super', 'sub', 'text-top',
-                'text-bottom') or (
+                'text-bottom', 'top', 'bottom') or (
                 isinstance(valign, (float, int)) and abs(valign) != 0)
-        issup = valign in ('super', 'text-top') or (
+        issup = valign in ('super', 'text-top', 'top') or (
             isinstance(valign, (float, int)) and valign > 0)
         vtag = 'sup' if issup else 'sub'
         if not_baseline and not ignore_valign and tag not in NOT_VTAGS and not isblock:
@@ -484,6 +484,7 @@ class MobiMLizer(object):
             parent = bstate.para if bstate.inline is None else bstate.inline
             if parent is not None:
                 vtag = etree.SubElement(parent, XHTML(vtag))
+                vtag = etree.SubElement(vtag, XHTML('small'))
                 # Add anchors
                 for child in vbstate.body:
                     if child is not vbstate.para: