Animate CSS background-position with smooth results (sub-pixel animation) - css

Question

I'm trying to animate the background-position of a div, slowly, but without it having jerky movement. You can see the result of my current efforts here:
http://jsfiddle.net/5pVr4/2/
#-webkit-keyframes MOVE-BG {
from {
background-position: 0% 0%
}
to {
background-position: 187% 0%
}
}
#content {
width: 100%;
height: 300px;
background: url(http://www.gstatic.com/webp/gallery/1.jpg) 0% 0% repeat;
text-align: center;
font-size: 26px;
color: #000;
-webkit-animation-name: MOVE-BG;
-webkit-animation-duration: 100s;
-webkit-animation-timing-function: linear;
-webkit-animation-iteration-count: infinite;
}
I have been at this for hours and can't find anything that will animate slowly and smoothly at a sub-pixel level. My current example was made from the example code on this page: http://css-tricks.com/parallax-background-css3/
The smoothness of animation I'm after can be seen on this page's translate() example:
http://css-tricks.com/tale-of-animation-performance/
If it can't be done with the background-position, is there a way to fake the repeating background with multiple divs and move those divs using translate?

Answer 1

Checkout this example:
#content {
height: 300px;
text-align: center;
font-size: 26px;
color: #000;
position:relative;
}
.bg{
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
z-index: -1;
background: url(http://www.gstatic.com/webp/gallery/1.jpg) 0% 0% repeat;
animation-name: MOVE-BG;
animation-duration: 100s;
animation-timing-function: linear;
animation-iteration-count: infinite;
}
#keyframes MOVE-BG {
from {
transform: translateX(0);
}
to {
transform: translateX(-187%);
}
}
<div id="content">Foreground content
<div class="bg"></div>
</div>
http://jsfiddle.net/5pVr4/4/

Answer 2

Animating background-position will cause some performance issues. Browsers will animate transform properties much cheaply, including translate.
Here is an example using translate for an infinite slide animation (without prefixes):
http://jsfiddle.net/brunomuller/5pVr4/504/
#-webkit-keyframes bg-slide {
from { transform: translateX(0); }
to { transform: translateX(-50%); }
}
.wrapper {
position:relative;
width:400px;
height: 300px;
overflow:hidden;
}
.content {
position: relative;
text-align: center;
font-size: 26px;
color: #000;
}
.bg {
width: 200%;
background: url(http://www.gstatic.com/webp/gallery/1.jpg) repeat-x;
position:absolute;
top: 0;
bottom: 0;
left: 0;
animation: bg-slide 20s linear infinite;
}

Answer 3

You should adjust your HTML and CSS little bit
Working Demo
HTML
<div id="wrapper">
<div id="page">
Foreground content
</div>
<div id="content"> </div>
</div>
CSS
#-webkit-keyframes MOVE-BG {
from { left: 0; }
to { left: -2000px; }
}
#wrapper {
position:relative;
width:800px;
height: 300px;
overflow:hidden;
}
#page {
text-align: center;
font-size: 26px;
color: #000;
}
#content {
width: 2000px;
height: 300px;
background: url(http://www.gstatic.com/webp/gallery/1.jpg) 0% 0% repeat;
position:absolute;
top: 0;
left: 0;
z-index:-1;
-webkit-animation-name: MOVE-BG;
-webkit-animation-duration: 100s;
-webkit-animation-timing-function: linear;
-webkit-animation-iteration-count: infinite;
}