css - CSS3 Fade Effect

Question

a {
    float: left;
    width: 32px;
    height: 32px;
    text-align: left;
    text-indent:-9999px;
    background: url('../img/button.png') no-repeat 0 0;

    -webkit-transition: background 300ms ease-in 2s; /* property duration timing-function delay */
    -moz-transition: background 300ms ease-in 2s;
    -o-transition: background 300ms ease-in 2s;
    transition: background 300ms ease-in 2s;


    -webkit-transition-property: background;
    -webkit-transition-duration: 300ms;
    -webkit-transition-timing-function: ease-in;
    -webkit-transition-delay: 100ms;

    -moz-transition-property: background;
    -moz-transition-duration: 300ms;
    -moz-transition-timing-function: ease-in;
    -moz-transition-delay: 100ms;

    -o-transition-property: background;
    -o-transition-duration: 300ms;
    -o-transition-timing-function: ease-in;
    -o-transition-delay: 100ms;

    transition-property: background;
    transition-duration: 300ms;
    transition-timing-function: ease-in;
    transition-delay: 100ms;

}

a:hover {
    background:position: 0 -32px;
}

.. currently it has scroll up/down effect, but I want the background to change with fade effect, what should I change in the CSS?

Thanks!

Answer 1

You can't transition between two background images, as there's no way for the browser to know what you want to interpolate. As you've discovered, you can transition the background position. If you want the image to fade in on mouse over, I think the best way to do it with CSS transitions is to put the image on a containing element and then animate the background colour to transparent on the link itself:

span {
    background: url(button.png) no-repeat 0 0;
}
a {
    width: 32px;
    height: 32px;
    text-align: left;
    background: rgb(255,255,255);

    -webkit-transition: background 300ms ease-in 200ms; /* property duration timing-function delay */
    -moz-transition: background 300ms ease-in 200ms;
    -o-transition: background 300ms ease-in 200ms;
    transition: background 300ms ease-in 200ms;
    }
a:hover {
    background: rgba(255,255,255,0);
}