CSS: How to scale an image from the center instead of top-left

Add this to the div:hover:

transform: translateX(-25%) translateY(-25%);

Here is the Fiddle: http://jsfiddle.net/3ya98xh8/4/

may as well throw my solution up in case it is helpful to anyone:

::CSS::

img {
    width: 100%; max-width: 100%;
}
div {
    position: absolute; left: 50%; top: 50%;
    margin-left: -125px; margin-top: -100px;
    width: 250px;
    transition: all 2s ease-in-out;
}
div:hover {
    margin-left: -200px; margin-top: -150px;
    width: 400px;
}

::HTML::

<div>
    <a href="http://photobucket.com/images/cat" target="_blank">
        <img src="http://i583.photobucket.com/albums/ss278/campipr/coolcat.gif" border="0" alt="cat photo: cat coolcat.gif"/>
    </a>
</div>

::Fiddle:: http://jsfiddle.net/Eolis/3ya98xh8/5/

Just replace width: 400px; with transform: scale(2,2) on :hover.

img {
    width: 100%; max-width: 100%;
}
div {
    position: absolute; left: 20%; top: 20%;
    width: 250px;
    transition: all 2s ease-in-out;
}
div:hover {
    transform: scale(2,2)
}

<div>
    <a href="http://photobucket.com/images/cat" target="_blank">
        <img src="http://i583.photobucket.com/albums/ss278/campipr/coolcat.gif" border="0" alt="cat photo: cat coolcat.gif"/>
    </a>
</div>

Don't forget to set transform-origin

.current{
    top: 0px;
    left: 0px;
    z-index: 2;
    opacity: 1;
    transform: scale(0.9, 0.9);
    transition: opacity 1.6s ease-out 0s, transform 7.2s linear 0s;
    transform-origin: center center;
    animation: normal;
}

https://css-tricks.com/almanac/properties/t/transform-origin/