diff --git a/src/calibre/ebooks/html.py b/src/calibre/ebooks/html.py
index f14e153057..634963e775 100644
--- a/src/calibre/ebooks/html.py
+++ b/src/calibre/ebooks/html.py
@@ -798,8 +798,9 @@ class Processor(Parser):
             if face is not None:
                 faces = []
                 for face in face.split(','):
-                    if ' ' in face:
-                        face = "%s" % face
+                    face = face.strip()
+                    if ' ' in face and not (face[0] == face[-1] == '"'):
+                        face = '"%s"' % face.replace('"', r'\"')
                     faces.append(face)
                 for generic in ('serif', 'sans-serif', 'monospace'):
                     if generic in faces:
diff --git a/src/calibre/ebooks/mobi/mobiml.py b/src/calibre/ebooks/mobi/mobiml.py
index 6193fbba13..da0da7c543 100644
--- a/src/calibre/ebooks/mobi/mobiml.py
+++ b/src/calibre/ebooks/mobi/mobiml.py
@@ -115,7 +115,7 @@ class MobiMLizer(object):
         if isinstance(ptsize, basestring):
             return ptsize
         embase = self.profile.fbase
-        if ptsize < embase:
+        if round(ptsize) < embase:
             return "%dpt" % int(round(ptsize))
         return "%dem" % int(round(ptsize / embase))
 
diff --git a/src/calibre/ebooks/mobi/writer.py b/src/calibre/ebooks/mobi/writer.py
index 2a7a3addfa..c1b6e87d72 100644
--- a/src/calibre/ebooks/mobi/writer.py
+++ b/src/calibre/ebooks/mobi/writer.py
@@ -346,7 +346,9 @@ class MobiWriter(object):
         format = image.format
         changed = False
         if image.format not in ('JPEG', 'GIF'):
-            format = 'GIF'
+            width, height = image.size
+            area = width * height
+            format = 'GIF' if area <= 40000 else 'JPEG'
             changed = True
         if dimen is not None:
             image.thumbnail(dimen, Image.ANTIALIAS)
@@ -481,7 +483,11 @@ class MobiWriter(object):
 
 
 def option_parser():
+    profiles = Context.PROFILES.keys()
+    profiles.sort()
+    profiles = ', '.join(profiles)
     from calibre.utils.config import OptionParser
+    from optparse import OptionGroup
     parser = OptionParser(usage=_('%prog [options] OPFFILE'))
     parser.add_option(
         '-o', '--output', default=None, 
@@ -495,6 +501,16 @@ def option_parser():
     parser.add_option(
         '-v', '--verbose', default=False, action='store_true',
         help=_('Useful for debugging.'))
+    group = OptionGroup(parser, _('Profiles'), _('Device renderer profiles. '
+        'Affects conversion of default font sizes and rasterization '
+        'resolution.  Valid profiles are: %s.') % profiles)
+    group.add_option(
+        '--source-profile', default='Browser', metavar='PROFILE',
+        help=_("Source renderer profile. Default is 'Browser'."))
+    group.add_option(
+        '--dest-profile', default='CybookG3', metavar='PROFILE',
+        help=_("Destination renderer profile. Default is 'CybookG3'."))
+    parser.add_option_group(group)
     return parser
 
 def oeb2mobi(opts, inpath):
@@ -504,9 +520,17 @@ def oeb2mobi(opts, inpath):
     if outpath is None:
         outpath = os.path.basename(inpath)
         outpath = os.path.splitext(outpath)[0] + '.mobi'
+    source = opts.source_profile
+    if source not in Context.PROFILES:
+        logger.error(_('Unknown source profile %r') % source)
+        return 1
+    dest = opts.dest_profile
+    if dest not in Context.PROFILES:
+        logger.error(_('Unknown destination profile %r') % dest)
+        return 1
     compression = PALMDOC if opts.compress else UNCOMPRESSED
     imagemax = MAX_IMAGE_SIZE if opts.rescale_images else None
-    context = Context('Firefox', 'EZReader')
+    context = Context(source, dest)
     oeb = OEBBook(inpath, logger=logger)
     tocadder = HTMLTOCAdder()
     tocadder.transform(oeb, context)
@@ -535,8 +559,8 @@ def main(argv=sys.argv):
         parser.print_help()
         return 1
     inpath = args[0]
-    oeb2mobi(opts, inpath)
-    return 0
+    retval = oeb2mobi(opts, inpath)
+    return retval
 
 if __name__ == '__main__':
     sys.exit(main())
diff --git a/src/calibre/ebooks/oeb/profile.py b/src/calibre/ebooks/oeb/profile.py
index f57257907f..032fe5e5ff 100644
--- a/src/calibre/ebooks/oeb/profile.py
+++ b/src/calibre/ebooks/oeb/profile.py
@@ -45,7 +45,7 @@ PROFILES = {
                 fsizes=[14, 14, 16, 18, 20, 22, 24, 26]),
     
     # No clue on usable screen size; DPI should be good
-    'EZReader':
+    'HanlinV3':
         Profile(width=584, height=754, dpi=168.451, fbase=16,
                 fsizes=[12, 12, 14, 16, 18, 21, 24, 28]),
 
@@ -57,13 +57,15 @@ PROFILES = {
         Profile(width=525, height=640, dpi=168.451, fbase=16,
                 fsizes=[12, 12, 14, 16, 18, 21, 24, 28]),
     
-    'Firefox':
+    'Browser':
         Profile(width=800, height=600, dpi=100.0, fbase=12,
                 fsizes=[5, 7, 9, 12, 13.5, 17, 20, 22, 24])
     }
 
 
 class Context(object):
+    PROFILES = PROFILES
+    
     def __init__(self, source, dest):
         if source in PROFILES:
             source = PROFILES[source]
diff --git a/src/calibre/ebooks/oeb/transforms/manglecase.py b/src/calibre/ebooks/oeb/transforms/manglecase.py
index 07fec10fb2..3a3d91364f 100644
--- a/src/calibre/ebooks/oeb/transforms/manglecase.py
+++ b/src/calibre/ebooks/oeb/transforms/manglecase.py
@@ -40,8 +40,9 @@ class CaseMangler(object):
         self.oeb.manifest.add(id, href, CSS_MIME, data=CASE_MANGLER_CSS)
         for item in self.oeb.spine:
             html = item.data
+            relhref = item.relhref(href)
             etree.SubElement(html.find(XHTML('head')), XHTML('link'),
-                             rel='stylesheet', href=href, type=CSS_MIME)
+                             rel='stylesheet', href=relhref, type=CSS_MIME)
             stylizer = Stylizer(html, item.href, self.oeb, self.profile)
             self.mangle_elem(html.find(XHTML('body')), stylizer)