Mobile safari position:fixed z-index glitch when scrolling

Question

I know iPhones used to not support position:fixed, but now it does and I'm seeing a weird glitch when I scroll a fixed position element behind other elements with higher z-index. The fixed positions element with the lower z-index appears in front momentarily, which looks really bad. Is there a way to prevent this?

I tried adding -webkit-transform: translate3d(0, 0, 0); to the fixed element and it doesn't seem to help this problem.

Here is a jsfiddle as well.

Update I added transform:translateZ(x) in addition to the z-index and it did not fix the problem.

Update2 I added -webkit prefix and this DOES fix the z-index problem on an mobile Safari, but also causes the position:fixed to work incorrectly in desktop Chrome.

Solution 1

z-index is not reliable with position:fixed, as shown in this fiddle: http://jsfiddle.net/mZMkE/2/ use translateZ transformation instead.

transform:translateZ(1px);

on your page elements.

EDIT: In your code, Add this css:

.bla, .projects, .contact  {
      -webkit-transform:translateZ(1px);
      -moz-transform:translateZ(1px);
      -o-transform:translateZ(1px);
      transform:translateZ(1px);
}

and then remove z-index refs from those elements and .intro.

Solution 2

Update 1: I added transform:translateZ(x) in addition to the z-index and it did not fix the problem.

Update 2: I added -webkit- prefix and this DOES fix the z-index problem on mobile Safari, but also causes the position:fixed to work incorrectly in desktop Chrome. "

Then try to wrap -webkit-transform:translateZ(x) in a mobile specific media query.
For example:

@media only screen and (min-device-width : ... ) and (max-device-width : ... ) {
    .whatever {
        -webkit-transform: translateZ(x)
    }
}

So in this case it won't do anything on desktop Chrome

Solution 3

I tried the solution accepted as an answer in a specific case when I needed to set different position in the stack of different layers, but that alone didn't work both in desktop browsers (firefox and chrome) and Safari iOS

I came out with this hack which uses both translateZ and z-index for each div, which is working in those platforms. The order of translateZ and z-index is important. For setting each layers position is

-webkit-transform:translateZ(1px);
-moz-transform:translateZ(1px);
-o-transform:translateZ(1px);
transform:translateZ(1px);
position: relative; 
z-index: 1; 

I used the same value for the z-index and translateZ just for consistency, it is not necessary. See working example http://jsbin.com/peyehufo/5

Solution 4

I'm not advocating for this solution, but it's the best I've got at the moment...

In order to replicate the effect of z-index with position fixed on an iPhone, it seems to require two techniques together:

1. As suggested by @tnt above, use transform:translateZ(n) where z-index is used to get mobile safari to handle the stack order correctly. This appears to have the unfortunate side-effect of causing the position:fixed to stop working...

2. Instead of position:fixed, use a javascript technique like this to fake it.

I haven't tested this thoroughly (because I'm not going to do it), but it seems to work fairly well. Although the "fixed" element seems to stutter a bit.

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