Jitter on chrome css animations

Question

Trying to make a css animation that fades in on an image from the center by using two centered divs with the same background image [svg], and animating their width and background position. The problem is, on chrome, there's a terrible jitter problem (Maybe from chrome cycling through the animation steps, instead of doing them simultaneously?)

Here's the jsfiddle: http://jsfiddle.net/evankford/s2uRV/4/, where you can see the jitter problem on the left one (which has simultaneous width animation and background-position animation).

Relevant Code (sorry for some leftover stuff from the site it's in)

HTML:

    <div class="underheader-wrapper uhw-title">
       <div class="underheader uhleft undertitle">&nbsp;</div>
       <div class="underheader uhright undertitle">&nbsp;</div>
    </div>

And CSS:

   .undertitle {
-webkit-backface-visibility: hidden;
 -webkit-transform: translateZ(0);
background-image:url(http://cereusbright.com/newsite/presskit/images/underheader.svg);
}

.underheader-wrapper {
position: relative;
margin:  auto;
width:320px;
height:100px;
}

.underheader {
-webkit-backface-visibility: hidden;
position:absolute;
width: 0px;
height:100px;
opacity: 0;
background-size: 320px 60px;
background-repeat: no-repeat;
-moz-animation-delay: 3s; -webkit-animation-delay:3s;
-moz-animation-duration: 3s; -webkit-animation-duration: 3s;
-moz-animation-name: part1; -webkit-animation-name:part1;
-webkit-animation-fill-mode:forwards;
-moz-animation-fill-mode:forwards}

.uhleft {
background-position: -160px 40px;
right: 160px;
-webkit-backface-visibility: hidden;
-moz-animation-delay: 3s; -webkit-animation-delay:3s;
-moz-animation-duration: 3s; -webkit-animation-duration: 3s;
-moz-animation-name: part2; -webkit-animation-name:part2;
-webkit-animation-fill-mode:forwards; 
-moz-animation-fill-mode:forwards}

.uhright {
background-position: -160px 40px;
left: 160px;}

@-webkit-keyframes part1 {
from {
    width: 0px;
    opacity: 0;
}
to {
    width: 160px;
    opacity: 1;
}}

@-webkit-keyframes part2 {
from {
    background-position:-160px 40px;
    width: 0px;

    opacity: 0;
}
to {
    width: 160px;
    background-position: 0px 40px;
    opacity: 1;
}}

@-moz-keyframes part1 {
from {
    width: 0px;
    opacity: 0;
}
to {
    width: 160px;
    opacity: 1;
}}

@-moz-keyframes part2 {
from {
    background-position:-160px 40px;
    width: 0px;
    opacity: 0;
}
to {
    background-position: 0px 40px;
    width: 160px;
    opacity: 1;
}}

Am I stuck with this jitter? I already did a JQuery version, and found people saying that CSS was cleaner/smoother, but the jitter still happens.

Answer 1

Okay, didn't find a way to use dual divs to achieve this goal. Instead, I did something like this.

<div class="outer">
     <div class="middle">
            <div class"inner">
             &nbsp
            </div>
      </div>
</div>

and then styled them

.outer {
position: relative;
width:321px;
height:100px;
padding: 15px;
} 

.middle {
text-align: center;
position: absolute;
left: 160px;
margin:auto;
background-image:url(images/underheader.svg);
background-position:center center;
background-size: 320px 70px;
background-repeat: no-repeat;
/*all the animation stuff */
 }

.inner {
position: relative;
display: inline-block;
width: 0px;
height: 100px;
/* all the animation stuff */
 }

I then animated the middle div from left:160px to left: 0px and the inner div from width: 0px to width: 320px. I used CSS animation, though it could easily be done with jquery or CSS transitions.

Answer 2

The delay you see on Chrome is given by -webkit-animation-delay:3s;. Change it to -webkit-animation-delay:0s; and you'll see it will start fade in immediately.