I can reproduce this at en.wp today, but not at en.wikipedia.beta.wmflabs.org, so presumably the problem has already been fixed.

Confirmed with http://en.wikipedia.beta.wmflabs.org/wiki/User:Jdforrester_(WMF)/Bug_73320 – marking as FIXED.

Created attachment 17122
ISBN is displayed in red

Attached:

I copied
{{cite book|isbn=123456789X|url = http://www.amazon.com|title = Fish}} from http://en.wikipedia.beta.wmflabs.org/wiki/User:Jdforrester_(WMF)/Bug_73320 and pasted it into test2 - look at the attached screenshot.

<a href="/w/index.php?title=International_Standard_Book_Number&amp;action=edit&amp;redlink=1" class="new" title="International Standard Book Number (page does not exist)">ISBN</a>

@media screen

a.new:visited, #p-personal a.new:visited {
. 
color: #a55858;

ISBN is still red.

(In reply to etonkovidova from comment #4)

I copied
{{cite book|isbn=123456789X|url = http://www.amazon.com|title = Fish}} from
http://en.wikipedia.beta.wmflabs.org/wiki/User:Jdforrester_(WMF)/Bug_73320
and pasted it into test2 - look at the attached screenshot.

<a
href="/w/index.php?title=International_Standard_Book_Number&amp;
action=edit&amp;redlink=1" class="new" title="International Standard Book
Number (page does not exist)">ISBN</a>

@media screen

a.new:visited, #p-personal a.new:visited {
. 
color: #a55858;

ISBN is still red.

Yeah, because the word "ISBN" links to a page that doesn't exist. This is about the number being red.