I am using that gif image from PayPal
https://www.paypalobjects.com/en_US/i/btn/btn_buynow_LG.gif
On PayPal’s website, the area around that button appears as white/transparent.
When I use that same image as a background-image in CSS, for my own button “Buy now”, the area is grey around it.
Why is that? I am using Safari.
Try to add
background-color:transparent: