Png button black box

Site URL: http://www.alexverhaest.com/invitation

Hi there, 

I'm using two transparent png's as buttons. A black border keeps appearing around them though. How can I avoid this ?

Thanks 

1 hour ago, Alex_v said:

Site URL: http://www.alexverhaest.com/invitation

Hi there, 

I'm using two transparent png's as buttons. A black border keeps appearing around them though. How can I avoid this ?

Thanks 

Do you mean something like this?