CSS3 淡入淡出效果

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;
}

..目前它有向上/向下滚动效果，但我希望背景随着淡入淡出效果而改变，我应该在 CSS 中更改什么？

谢谢!

Answer 1

您不能在两个背景图像之间转换，因为浏览器无法知道您想要插入什么。正如您所发现的，您可以转换背景位置。如果您希望图像在鼠标悬停时淡入，我认为使用 CSS 过渡的最佳方法是将图像放在包含元素上，然后将链接本身的背景颜色设置为透明动画:

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);
}