From 9825a47254914562e80c06102ff109a13a75ab2f Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 17 Jul 2010 17:56:14 -0600
Subject: [PATCH] Conversion pipeline: Handle elements with percentage sizes
 that are children of zero size parents correctly. Fixes #6155 (error
 converting epub to mobi)

---
 src/calibre/ebooks/oeb/stylizer.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/calibre/ebooks/oeb/stylizer.py b/src/calibre/ebooks/oeb/stylizer.py
index 4789899fbf..f465935376 100644
--- a/src/calibre/ebooks/oeb/stylizer.py
+++ b/src/calibre/ebooks/oeb/stylizer.py
@@ -475,7 +475,8 @@ class Style(object):
             value = float(m.group(1))
             unit = m.group(2)
             if unit == '%':
-                base = base or self.width
+                if base is None:
+                    base = self.width
                 result = (value / 100.0) * base
             elif unit == 'px':
                 result = value * 72.0 / self._profile.dpi