Problem
I'm trying to make a layer appear like it's a wall falling down, revealing the layer behind it. I've setup two fixed div positions. The "Wall" div has a z-index of 9999, the "Background" div has a z-index of 0;
In Webkit browsers (Safari/IOS) that I've tested, it seems like once the animation starts on the "wall", the z-indexes are lost or ignored, causing the "wall" layer to abruptly disappear behind the background div.
Any ideas on how to preserve the z-indexes of the layers? Thanks in advance!
Example Code (note: jsFiddle at the bottom)
HTML Code
<div id="wall">
This is the wall
</div>
<div id="background">
This is the background
</div>
<button id="start" style="float: right;">
Flip Down
</button>
Some javascript to enable the button
$('#start').click(function(){
alert('Should Fall Down like a wall, revealing the background');
$('#wall').addClass('animated flipDown');
});
CSS Code (cribbed from animate.css)
#wall{
background-color: #F00;
width: 100px;
height: 100px;
position:fixed;
top:0;
left:0;
z-index: 9999;
}
#background{
background-color: #00F;
width: 100px;
height: 100px;
position:fixed;
top:0;
left:0;
z-index: 0;
}
.animated {
-webkit-animation-duration: 1s;
animation-duration: 1s;
-webkit-animation-fill-mode: both;
animation-fill-mode: both;
}
/*** flipDown ***/
@-webkit-keyframes flipDown {
0% {
-webkit-transform: perspective(400px) rotateX(0deg);
transform: perspective(400px) rotateX(0deg);
-webkit-transform-style: flat;
opacity: 1;
}
100% {
-webkit-transform: perspective(400px) rotateX(90deg);
transform: perspective(400px) rotateX(90deg);
-webkit-transform-style: flat;
opacity: 1;
}
}
@keyframes flipDown {
0% {
-webkit-transform: perspective(400px) rotateX(0deg);
-ms-transform: perspective(400px) rotateX(0deg);
transform: perspective(400px) rotateX(0deg);
opacity: 1;
}
100% {
-webkit-transform: perspective(400px) rotateX(90deg);
-ms-transform: perspective(400px) rotateX(90deg);
transform: perspective(400px) rotateX(90deg);
opacity: 0;
}
}
.flipDown {
-webkit-animation-name: flipDown;
animation-name: flipDown;
-webkit-backface-visibility: visible !important;
-ms-backface-visibility: visible !important;
backface-visibility: visible !important;
-webkit-transform-origin: bottom;
-ms-transform-origin: bottom;
transform-origin: bottom;
}
jsFiddle
http://jsfiddle.net/3mHe2/2/
Check out the differences in Safari vs Chrome.
Bookmark this question.
You set z-index on a static element By default, every element has a position of static. z-index only works on positioned elements (relative, absolute, fixed, sticky) so if you set a z-index on an element with a static position, it won't work.
z-index only affects elements that have a position value other than static (the default). Elements can overlap for a variety of reasons, for instance, relative positioning has nudged it over something else. Negative margin has pulled the element over another. Absolutely positioned elements overlap each other.
No, it isn't inherited. You can see it in MDN article. However, be aware that z-index sets the z-position relatively to the stacking context. And a positioned element with non auto z-index will create an stacking context.
My rotating element wasn't suitable to have a neighbour to the background, but I fixed it by applying
transform: translateZ(1000px);
transform-style: preserve-3d;
to the parent of the rotating element. Safari now thinks it's 1000px infront of the background.
Found a solution. Hopefully this helps someone in the future.
It turns out that there is a "bug" in the safari versions of webkit. When a 3d css animation is playing, the original z-indexes are lost. Instead, it seems like the animating pieces are put into a separate z-index "group" that is separate from the rest of the z-indexes of the DOM.
The solution is to join the backdrop div and the wall div into the same z-index group by wrapping it in a div with a webkit-transform that doesn't change anything. That causes the backdrop and wall to be children of the wrapper div and the z-indexing of the respective children are preserved.
<div id="wrapper" style="-webkit-transform: translate3d(0px, 0px, 0px);">
<div id="wall">
This is the wall
</div>
<div id="background">
This is the background
</div>
</div>
I believe it is the same or similar issue to this:
css z-index lost after webkit transform translate3d
I ran into this issue and nothing would fix it until i added perspective to the parent container of the item that should be behind.
.wrap{
perspective: 1000px;
}
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