Here is the code I use to add a hover effect to button links.

Copy and paste this code into your stylesheet:

a img {
opacity:.40;
filter:alpha(opacity=40);
filter: “alpha(opacity=40)”;
filter:alpha(opacity=40);
}

a:hover img{
opacity:1;
filter:alpha(opacity=100);
filter: “alpha(opacity=100)”;
filter:alpha(opacity=100);
}

You can see an example of this here.

That’s it!