--- redcloth3.rb.orig	2017-07-26 14:37:03.975440398 +0200
+++ redcloth3.rb	2017-07-26 14:39:39.975434819 +0200
@@ -514,7 +514,7 @@
         atts
     end
 
-    STYLES_RE = /^(color|width|height|border|background|padding|margin|font|text|float)(-[a-z]+)*:\s*((\d+%?|\d+px|\d+(\.\d+)?em|#[0-9a-f]+|[a-z]+)\s*)+$/i
+    STYLES_RE = /^(color|width|max-width|height|border|background|padding|margin|font|text|float)(-[a-z]+)*:\s*((\d+%?|\d+px|\d+(\.\d+)?em|#[0-9a-f]+|[a-z]+)\s*)+$/i
 
     def sanitize_styles(str)
       styles = str.split(";").map(&:strip)