remove the black underline on hover for an image link

remove the black underline on hover for an image link

I'm havins some difficulty with my image links in google chrome. the
images get a black underline when they have been hovered over, how do i
remove this I've tried
a {
color: #000;
&:visited {
color: #666;
}
&:hover {
outline-style:none;
box-shadow:none;
border-color:transparent;
}
}
and
a {
color: #000;
&:visited {
color: #666;
}
&:hover {
border-style:none;
}
}
along with loads of other things but nothing seems to work, the css does
effect it but not how i want it to, Any help would really be appreciated.