I'm trying to transition on hover with css over a thumbnail so that on hover, the background gradient fades in. The transition isn't working, but if I simply change it to an rgba() value, it works fine. Are gradients not supported? I tried using an image too, it won't transition the image either.
I know it's possible, as in another post someone did it, but I can't figure out how exactly. Any help> Here's some CSS to work with:
#container div a {
-webkit-transition: background 0.2s linear;
-moz-transition: background 0.2s linear;
-o-transition: background 0.2s linear;
transition: background 0.2s linear;
position: absolute;
width: 200px;
height: 150px;
border: 1px #000 solid;
margin: 30px;
z-index: 2
}
#container div a:hover {
background: -webkit-gradient(radial, 100 75, 100, 100 75, 0, from(rgba(0, 0, 0, .7)), to(rgba(0, 0, 0, .4)))
}
This is now possible using the @property workaround. Please see @Mahozad's answer.
Original Answer:
Gradients don't support transitions yet (although the current spec says they should support like gradient to like gradient transitions via interpolation.).
If you want a fade-in effect with a background gradient, you have to set an opacity on a container element and 'transition` the opacity.
(There have been some browser releases that supported transitions on gradients (e.g IE10. I tested gradient transitions in 2016 in IE and they seemed to work at the time, but my test code no longer works.)
October 2018 Update: Gradient transitions with un-prefixed new syntax [e.g. radial-gradient(...)] now confirmed to work (again?) on Microsoft Edge 17.17134. I don't know when this was added. Still not working on latest Firefox & Chrome / Windows 10.