a:link{
    transition: color .05s;
}

img{
    opacity: 0.25;
    transition: opacity 500ms;
}

img:hover{
    opacity: 1;
}

figure {
    position: relative;
}

figure img{
    position: absolute;
    top: 0;
    left: 0;
}

figure .visible{
    opacity: 1;
}

figure .hidden{
    opacity: 0;
}

figure:hover .hidden{
    opacity: 1;
}

figure:hover .visible{
    opacity: 0;
}

img {
    width: 300px;
}