Problems with CSS when using Lightbox2

Im using Lightbox 2 to display some images. It works but now 100%. The next and prev buttons do not appear.
Im using the following CSS code. Im using VWD 2005. I get the following errors 'base 64 is not a known CSS property and url(data:image/gif; base64:AAAA) is not a valid value for the 'background-image' property.
#prevLink, #nextLink{ width: 49%; height: 100%; background-image: url(data:image/gif; base64< ...