For some reason when you apply a background image to a tr in Safari/Chrome it renders it as if the rule applies to every td.
Firefox:
(source: whyp
it's bit late but, you can use "background-attachment : fixed" to solve this problem.
and in CSS
tr.bg { background-image : url(../PathToLeftBackground.png) repeat-y 50px 0px; background-attachment: fixed; }
and it works!