Q:

CSS Translate On Normal

I'm making a modal popup in CSS that will appear and and translate down (translateY) after clicking on the link. My problem is popup did appear but it already at downside. I know how to make translate on hover but I cant figure out how to translate this without hover. Can anyone give me some advice?
HTML
<a href='#A'>Open</a>
<div id='A' class='B'>
<div class='C'>
Test</div>
</div>

CSS
.B {
    position:fixed;
    top:0px;
    right:0px;
    bottom:0px;
    left:0px;
    background:rgba(0,0,0,0.8);
    opacity:0;
    z-index:99999;
    pointer-events:none;
}
.B:target {
    opacity:1;
    pointer-events:auto;
}
.B > .C {
    width:100px;
    height:100px;
    background:#FFF;
    background:-moz-linear-gradient(#FFF, #999);
    background:-webkit-linear-gradient(#FFF, #999);
    background:-o-linear-gradient(#FFF, #999);
    -webkit-border-radius:15px;
    -moz-border-radius:15px;
    -ms-border-radius:15px;
    -o-border-radius:15px;
    border-radius:15px;
    position:relative;
}
.C {
-webkit-transition: all 1s ease-out;
    -moz-transition: all 1s ease-out;
    -ms-transition: all 1s ease-out;
    -o-transition: all 1s ease-out;
    transition: all 1s ease-out;    
-webkit-transform: translate(0px, 50px);
-moz-transform: translate(0px, 50px);
-o-transform: translate(0px, 50px);
-ms-transform: translate(0px, 50px);
transform: translate(0px, 50px);
}

JSFiddle
http://jsfiddle.net/M5tcL/16/

A:

CSS transitions make changes on a property's value appear smooth to the viewer (tween?).
You don't ever change a css property's value here, so there is nothing to animate.
There has to be two css states with different values. You need javascript or a checkbox to make this work.
You can use javascript to toggle a class on the body element for example, or a checkbox with an associated label.
Then you can use
/* Normal state */
.C{
    opacity: 0;
    transition: all .3s;
}
/* Open state */
:checked ~ .C,
/* OR */
body.open .C{
    opacity: 1;
}

In this snippet example, opacity will get animated while changing between 0 and 1.

