lucy24 - 6:57 pm on May 4, 2013 (gmt 0)
Oh, wait. Does the actual image have a gradient? Then saving as png will probably send the filesize through the roof.
Doing it in CSS is definitely safer. How many versions of MSIE will you lose if you take this approach?
Remember also that your users will be seeing the page in their own everyday browser. So they'll see what they are accustomed to seeing.