From 448aa8497b2d1f1be157cec885f89d583003cc43 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Thu, 23 Sep 2010 20:23:11 -0600
Subject: [PATCH] Fix #6909 (Trouble in converting non drm prc file to epub)

---
 src/calibre/ebooks/oeb/transforms/flatcss.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/calibre/ebooks/oeb/transforms/flatcss.py b/src/calibre/ebooks/oeb/transforms/flatcss.py
index 7212bd33c6..7b83421097 100644
--- a/src/calibre/ebooks/oeb/transforms/flatcss.py
+++ b/src/calibre/ebooks/oeb/transforms/flatcss.py
@@ -219,7 +219,10 @@ class CSSFlattener(object):
                     fnums = self.context.source.fnums
                     if size[0] in ('+', '-'):
                         # Oh, the warcrimes
-                        esize = 3 + force_int(size)
+                        try:
+                            esize = 3 + force_int(size)
+                        except:
+                            esize = 3
                         if esize < 1:
                             esize = 1
                         if esize > 7: